tci<i  ^ 


FRANKLIN  INSTITUTE  LIBRARY 

PHILADELPHIA 

Class...G.<o7^.G  Book.S.C2..l.S..^  Accession,3....G..O.s5^.<o 

Given  hy}Y£W.j/.C.z]%Shl.p.Lujldia.^(2i. 

and  may  be  renewed. 

B9OKS  LOST  OR  DAMAGED  must  be 
paid  for  or  loss  explained. 

EMPLOYEES  MUST  NOT  exchange  books 
with  each  other  without  having  them  re- 
charged at  the  library. 

UPON  LEAVING  THE  EMPLOY  of  this 
Corporation  all  books  must  be  returned  before 
receiving  final  pay. 

THIS    PRIVILEGE   can   be  revoked  at 
any  time. 

CLASS  ^"^^ 
BOOK  "^W^^ 

ACCESSION             C  . 

N.Y.S.  Corp.  Form  715— 1M— 3-Feb-20 

Digitized  by 

the  Internet  Archive 

in  2015 

https://archive.org/details/redleadhowtouseiOOsabi 


BOOKS  BY 

A.  H.  SABIN,  M.S.,  D.Sc. 

PUBLISHED  BY 

JOHN  WILEY  &  SONS,  Inc. 

The  Industrial  and  Artistic  Technology  of 
Paint  and  Varnish.  Second  edition,  revised 
and  enlarged.    473  pp.    191 7. 

Housepainting;  A  Book  for  the  Householder. 
Second  Edition,  revised  and  enlarged.  143  pp. 
1918. 

German  Varnish-making.  Authorized  translation 
from  the  text  of  Professor  Max  Bottler,  with 
extensive  additions  relating  to  American  prac- 
tice in  making  paint  and  varnish.  363  pp.  1912. 

Whitelead:  Its  Use  in  Paint.   133  pp.  1920. 

Red-lead  and  How  to  Use  It  in  Paint.  150  pp. 
1920. 


EXCEPTING  TECHNICAL  ILLUSTRA- 
TIONS OF  PITTING  AND  RUSTING 
ALL  PICTURES  IN  THIS  BOOK  ARE 
OF  STRUCTURES  PAINTED  WITH 
PASTE  RED-LEAD 


RED-LEAD 

AND 

HOW  TO  USE  IT 
IN  PAINT 


BY 

ALVAH  HORTON  SABIN,  M.S.,  D.Sc. 

AUTHOR  OF  "technology  OF  PAINT  AND  VARNISH,"  " WHITE-LEAD,"  ETC. 
MEMBER  OF  THE  AMERICAN  CHEMICAL  SOCIETY,  THE   SOCIETY  OF 
CHEMICAL  INDUSTRY,  THE  SOCIETY  FOR  TESTING  MATERIALS, 
THE  PAINT  AND  VARNISH  SOCIETY  (lONDON),  ETC. 
LECTURER  IN  NEW  YORK  UNIVERSITY 


CAMDEN,  N.  J. 


THIRD  EDITION 

REWRITTEN  AND  ENLARGED 


NEW  YORK 

JOHN  WILEY  &  SONS,  Inc. 

London:  CHAPMAN  &  HALL,  Limited 
1920 


Copyright,  191 7,  19 19,  1920, 
By  A.  H.  Sabin 


ftRAUNWORTH  &  CO. 
BOOK  MANUFACTURERS' 
BROOKLYN.  N.  Y. 


PREFACE  TO  THE  THIRD  EDITION 


In  191 6  the  writer  prepared  a  little  book  telling 
the  essential  facts  about  red-lead  paint;  which,  so 
far  as  he  knows,  was  the  first  attempt  to  put  them 
into  connected  and  workable  shape.  This  was  pub- 
lished by  the  author,  and  privately  circulated.  It 
appeared  to  meet  a  public  want;  one  well-known 
railway  company  ordered  twenty  copies;  as  many 
more  were  sent  on  request  at  various  times  to  the 
Bureau  of  Standards;  and  on  the  day  when  these 
sentences  are  written  a  request  was  received  from 
a  State  Highway  Commission  for  several.  A  sec- 
ond edition,  also  privately  published  by  the  author, 
containing  some  correctio,ns  and  with  important 
additions,  was  made  early  in  1919;  and  as  it  is  ap- 
parent that  considerable  advances  in  knowledge  of 
the  matters  discussed  have  developed  since  it  was 
first  written,  it  seems  proper  and  advisable  to  issue 
now,  in  the  ordinary  methods  of  the  publishing  busi- 
ness, what  may  properly  enough  be  called  a  new 
edition,  being  written  by  the  same  author  and  in- 
cluding much  of  the  original  text,  but  rewritten 
and  amplified  to  an  extent  so  considerable  as  to 
make  it  almost  a  new  book. 

vii 

•3(2,  dv5  <^ 


viii  Preface  to  the  Third  Edition 


The  truth  is  that  the  last  few  years  have  seen  a 
great  increase  of  interest  in  the  subject;  due,  no 
doubt,  to  the  rise  in  the  cost  of  bridges  and  other 
metal  structures,  which  makes  their  preservation 
more  important;  this  incidentally  leads  to  more  dis- 
cussion of  it  in  the  meetings  of  engineers;  and  partly 
to  the  comparatively  recent  introduction  of  red-lead 
in  paste  form,  which,  as  is  explained  in  the  text,  is 
made  possible  by  improvements  in  the  pigment,  and 
increases  its  availability  for  more  extensive  use. 
The  writer  is  willing  to  predict  that  the  next  step 
will  be  its  sale  as  a  liquid  paint,  ready  for  use;  and 
that  this  will  so  much  promote  its  use  as  a  finishing 
coat  and  for  general  repainting,  that  the  demand 
for  it  will  be  several  times  as  much  as  now;  perhaps 
will  equal  that  for  white-lead.  Holding  this  belief, 
which  is  based  on  thirty  years'  experience  and  study 
of  protective  coatings,  the  writer  has  tried  to  give 
information  as  to  the  character  of  these  liquid 
paints;  for  all  paint  must  be  reduced  to  this  form 
before  it  can  be  applied. 

In  the  text,  the  gallon  is  always  the  U.  S.  gallon 
of  231  cu.  in.,  which  is  one-sixth  less  than  the 
British  imperial  gallon  (or  the  latter  is  one-fifth 
more  than  the  U.  S.  gallon)  ;  but  tables  are  appended 
for  the  use  of  those  who  use  the  British  measures. 


PREFACE  TO  THE  FIRST  EDITION 


In  a  recent  communication  the  engmeer  of  the 
Illinois  state  highway  commission  described  a  bridge 
more  than  two  hundred  feet  long  over  the  Fox  river 
at  Ottawa,  in  which  rust  had  formed  between  the 
web-plate  of  the  rib  carrying  the  sidewalk,  and  the 
flanges  of  the  adjacent  sections,  developing  enough 
expansive  force  to  rupture  the  connecting  rivets, 
which  were  of  tough  and  ductile  material;  in  one 
place  there  was  ten  feet  with  only  one  unbroken 
rivet,  and  in  general  only  lo  per  cent  of  the  rivets 
connecting  the  upper  and  lower  halves  of  the  arch 
ribs  were  unbroken.  The  engineer  says:  ^'A  circus 
outfit  had  been  allowed  to  cross  the  bridge  a  short 
time  before  the  examination  was  made.  It  was  re- 
ported that  the  vibration  was  so  great  that  oil  lan- 
terns hung  from  the  overhead  sway  bracing  swung 
up  against  the  supports  with  sufficient  violence  to 
break  the  globes.  It  is  also  said  that  the  leading 
elephant  gingerly  placed  one  foot  on  the  bridge, 
then  with  a  snort  of  disgust  lumbered  down  stream 
a  couple  of  blocks  and  swam  across.'' 

The  writer  knew  of  an  attempt  to  lead  an  elephant 
across  an  old  bridge  over  the  Wisconsin  river  at 

ix 


X 


Preface  to  the  First  Edition 


Portage,  when  the  wise  beast  after  entering  the 
bridge  backed  out,  went  down  the  bank  and  swam 
across  the  deep  and  swift  river,  which  was  nearly 
seven  hundred  feet  wide.  It  might  be  a  good  plan 
for  every  state  to  have  an  elephant  for  a  bridge 
inspector. 

Highway  bridges  are  often  like  that;  and  while 
railway  bridges  are  fairly  well  cared  for,  steel  cars 
are  not  much  better.  The  whole  subject  of  painting 
structural  metal,  while  not  exactly  neglected,  seems 
to  get  more  serious  attention  from  the  supply  men 
than  from  the  engineers,  which  is  not  as  it  should 
be.  Engineering  is  not  all  a  matter  of  ingenious 
design;  that  is  a  part  of  it,  but  a  knowledge  of  ma- 
terials Is  just  as  important  and  paint  is  just  as  much 
engineering  material  as  steel  or  concrete,  and  is  en- 
titled to  just  as  respectful  consideration. 

For  thirty  years  the  writer  has  been  concerned 
with  these  problems;  and  for  a  long  time  has  had 
unusual  opportunities  for  knowing  about  lead  pig- 
ments. Although  these  are  everywhere  recognized 
as  important,  it  seems  to  him  that  red-lead  is  not 
known  as  well  as  it  should  be;  and  particularly  that 
the  great  advances  recently  made  in  its  production 
and  character  need  to  be  made  use  of  more  gen- 
erally; therefore,  he  has  thought  it  proper  to  set 
forth  in  this  public  way  his  views  and  knowledge 
of  the  matter;  and  while  he  acknowledges  his  in- 
debtedness to  many  others,  and  has  tried  to  avoid 
giving  opinions  which  are  not  shared  by  many  who 
are  competent  to  speak  on  the  subject,  no  one  else 


Preface  to  the  First  Edition 


xi 


IS  responsible  for  what  is  set  forth.  Red-lead  is 
not  only  an  important  but  an  interesting  substance; 
its  consumption  for  paint,  in  glass-making,  storage- 
batteries,  and  many  other  things  is  increasing  at  an 
unprecedented  rate,  and  any  intelligent  contribution 
to  a  knowledge  of  it  ought  to  be  worth  reading. 

A.  H.  Sabin. 


RED-LEAD  AND  HOW  TO  USE  IT 
IN  PAINT 


How  Litharge  Is  Made 

Lead  has  two  principal  oxides:  litharge  and  red- 
lead.  When  lead  is  melted  and  exposed  to  the  air 
it  combines  with  oxygen  from  the  air,  the  product 
being  the  protoxide,  or  litharge,  the  chemical  expres- 
sion for  which  is  PbO,  indicating  that  one  atom  of 
lead  (plumbum)  is  united  to  one  atom  of  oxygen. 
This  is  a  yellow  substance;  if  melted,  as  it  some- 
times is  in  process  of  making,  it  tends  on  cooling  to 
crystallize  in  flakes,  and  is  then  called  flake  litharge; 
but  if  the  temperature  is  skilfully  regulated  it  may  be 
in  the  condition  of  a  powder.  It  is  difficult  to  pre- 
vent melting  in  the  hottest  part  of  the  furnace,  hence 
litharge  is  generally  uneven  in  fineness,  having  both 
fine  and  coarse  particles;  the  latter  may  be  powdered 
by  passing  the  whole  of  the  litharge  through  a  suit- 
able mill,  if  necessary. 

How  Red-Lead  is  Made 

When  this  yellow  litharge  is  again  roasted,  in  con- 
tact with  air,  at  a  suitable  temperature,  it  takes  up 
a  little  more  oxygen  and  turns  red;  it  is  then  called 


2  Red-Lead  and  How  to  Use  it  in  Paint 

red-lead,  and  its  composition  is  expressed  by  the 
chemical  formula  Pb.-O^.  Although  it  contains  only 
a  third  more  oxygen  than  litharge,  it  is  quite  differ- 
ent from  it;  litharge  is  easily  decomposed  and  enters 
into  other  chemical  combinations,  while  red-lead  is 
more  stable;  when  exposed  to  the  air  litharge  is 
acted  on,  but  red-lead  is  quite  permanent.  Litharge 
is  the  form  in  which  lead  is  commonly  used  when  it 
is  desired  to  make  lead-containing  compounds,  while 
red-lead  is  used  hardly  ever  in  this  way  except  in 
glass-making;  at  the  intense  heat  of  melted  glass  the 
red-lead  enters  into  combination  with  it.  This  ex- 
plains why  it  is  so  much  better  than  litharge  for  an 
oil-paint  pigment,  and  why  the  durability  of  red-lead 
is  greater  in  proportion  to  its  freedom  from  litharge. 

When  the  litharge  is  put  into  the  red-lead  furnace 
the  portion  which  is  a  fine  dust  is  easily  and  com- 
pletely oxidized;  but  the  coarse  particles  become  red 
on  the  outside  while  they  contain  unchanged  litharge 
in  the  interior.  Even  prolonged  roasting  fails  to 
change  these  further.  This  coarse  red-lead,  as  a 
dry  powder,  probably  does  not  reflect  as  much  white 
light  as  that  which  is  much  finer;  at  any  rate  its 
color  is  a  deeper  and  darker  red,  the  very  fine  and 
highly  oxidized  sort  being  of  an  orange  shade, 
whence  it  is  sometimes  called  ^^orange  mineral.'' 

Orange  Mineral 

It  is  commonly  thought  that  orange  mineral  is 
produced  only  by  roasting  dry  powdered  white-lead 


Orange  Mineral 


s 


(carbonate)  ;  being  decomposed  by  heat,  the  car- 
bonic acid  is  driven  off,  and  the  resulting  Htharge 
is  roasted  into  a  high-grade  red-lead  of  an  orange- 
red  color;  and,  in  fact,  this  is  the  common  way  of 
making  it;  but  such  a  product  is  not  distinguishable 
from  any  other  red-lead  of  equal  fineness  and  purity. 
The  essential  preliminary  step  is  in  some  way  to  get 
the  litharge  into  the  condition  of  a  uniformly  very 
fine  powder.  This  may  be  done  by  prolonged  dry- 
grinding,  as  all  manufacturers  know;  there  is  no 
secret  about  this,  but  it  costs  money  to  do  it  and 
requires  a  suitable  plant.  It  can  be  shown,  however, 
that  the  money  is  well  spent,  if  a  product  of  the 
best  quality  is  desired. 

Probably  the  largest  use  of  red-lead  is  in  making 
and  maintaining  storage  batteries;  and  the  makers 
of  these  have  very  different  requirements  from  those 
for  paint.  They  mix  litharge  with  red-lead;  and  in 
fact  they  commonly  prefer  a  red-lead  only  partly  con- 
verted, containing  about  70  per  cent  true  red-lead 
or  PbsO,. 

In  the  old-fashioned  hand-operated  furnaces  it 
required  great  skill  (as  well  as  the  best  materials) 
to  make  the  modern  high  grades,  which  are  now 
made  in  mechanical  furnaces,  and  operated  by  expert 
workmen;  furnace  samples  are  taken  from  every 
pan  and  chemically  tested  before  the  charge  is  fin- 
ished, and  in  the  best  modern  plants  the  operator 
can  turn  out  anything  the  customer  wants.  Doubt- 
less it  will  always  be  more  expensive  to  make  highly- 
oxidized  red-lead,  but  as  it  is  now  done  by  machinery 


6 


Red-Lead  and  How  to  Use  it  in  Paint 


the  additional  cost  Is  less  than  would  naturally  be 
supposed;  and  the  high-grade  product  is  better  and 
more  economical,  as  will  be  later  explained,  than 
the  older  sort;  that  is,  for  paint;  not  for  battery 
oxide,  or  for  glass-making,  much  being  used  for  the 
latter  industry;  in  fact,  fine  cut-glass  tableware  con- 
tains actual  lead  to  the  amount  of  from  30  to  50 
per  cent  of  its  weight;  the  lead  gives  it  brilliancy 
of  luster,  and  good  working  quality  in  manufacture. 


Objections  to  Red-Lead 

But  this  does  not  make  the  best  paint.  While  it 
is  true  that  red-lead  has  for  more  than  a  hundred 
years  been  the  standard  paint  for  the  protection  of 
metal,  and  that  a  good  deal  of  this  was  made  of 
red-lead  containing  what  would  now  be  regarded 
as  an  excessive  amount  of  litharge,  it  is  also  true 
that  it  was  disliked  by  many,  both  painters  and  en- 
gineers. The  most  serious  objections  to  it  are  two: 
litharge  acts  on  oil  at  ordinary  temperatures,  the 
paint  becoming  viscid  and  ropy,  and  finally,  if  al- 
lowed to  stand,  making  a  hard,  compact,  heavy, 
cement-like  solid;  and  second,  such  red-lead  is  coarse, 
and  coarse  particles  in  paint  on  vertical  surfaces 
start  *^runs,"  the  paint  running  down  in  drops  and 
tear-like  masses,  leaving  too  little  in  their  trail,  and 
making  unsightly  lumps;  also  each  of  these  coarse 
particles  which  remains  in  place  extends  through  the 
entire  thickness  of  the  film  from  the  underlying  metal 


Objections  to  Red-Lead 


7 


to  the  atmosphere,  and  forms  a  weak  and  defective 
spot  in  the  film,  as  will  be  explained  later. 

A  paint  which  is  ropy  does  not  brush  out  into  a 
smooth,  uniform  film;  its  surface  is  composed  of 
alternate  furrows  and  ridges,  due  to  the  bristles  of 
the  brush  sticking  together  in  little  bunches;  at  the 
bottoms  of  the  furrows  the  paint  may  be  too  thin, 
and  in  the  ridges  the  excess  is  waste,  which  might 
be  economically  applied  to  covering  additional  sur- 
face; moreover,  a  rough  surface  collects  dirt,  which 
may  help  to  start  corrosion,  and  it  does  not  resist 
the  abrasive  action  of  the  wind  and  dust  as  well  as 
a  smooth  one.  This  fact  is  well  known;  it  is  recog- 
nized practise  to  leave  varnish  on  exterior  wood- 
work with  its  natural  glazed  surface,  which  will  last 
longer  than  one  which  has  been  rubbed  with  pumice, 
as  practised  on  interiors;  also  the  extremely  smooth 
surface  of  baked  enamels,  as  on  bicycle  frames  and 
the  like,  stands  wear  better  because  of  its  smooth- 
ness. 

Let  us  bear  in  mind  this  fundamental  fact,  that 
fine  (powdered)  litharge  makes  fine  red-lead,  and 
such  necessarily  contains,  other  things  being  equal, 
more  true  red-lead  (Pb304)  than  that  which  is 
coarser.  In  former  times  little  attention  was  paid 
to  its  analytical  composition;  chemical  analyses  were 
rarely  made,  while  now  every  batch  is  analyzed  be- 
fore it  is  drawn  from  the  furnace;  but  the  painter 
knew  that  he  liked  paint  made  with  a  fine  pigment, 
and  he  chose  fine  (and  therefore  highly  oxidized) 
red-lead  if  he  could  get  it,  and  so  the  fine  sorts  came 


8 


Red-Lead  and  How  to  Use  it  in  Paint 


to  be  known  as  ^^palnters'  red-lead,"  and  were  saved 
for  paint,  while  the  coarser  were  sold  for  glass- 
making  and  the  like.  In  this  way  painters'  red-lead 
increased  in  true  red-lead  to  80  per  cent,  then  85 
per  cent,  90  per  cent,  and  about  1909  the  U.  S.  gov- 
ernment engineers  agreed  to  call  for  94  per  cent, 
allowing  not  more  than  6  per  cent  residual  litharge; 
this  is  their  standard  now.  Such  a  product  is  finely 
powdered;  in  fact,  to  make  it  the  litharge  must  be 
well  ground  before  it  is  put  in  the  red-lead  furnace; 
and  the  large  proportion  of  stable  PbsO^  greatly 
retards  the  action  of  the  litharge  on  the  oil,  so  that 
its  brushing-out  quality  is  good.  Nevertheless,  if 
allowed  to  stand  in  oil  long  it  thickens  and  becomes 
viscous  and  finally  hard;  and  the  road  to  improve- 
ment obviously  runs  in  the  direction  of  making  it 
finer  in  texture  and  consequently  lower  in  litharge. 


What  High-grade  Red-Lead  Is 


It  has  been  found  that  certain  chemical  impuri- 
ties in  it  prevent,  or  at  least  retard,  this  effect;  but 
when  sufficiently  pure  materials  are  used,  and  care 
is  taken  to  prevent  the  introduction  of  impurities 
in  manufacture,  if  the  raw  material  is  ground  to 
an  impalpable  powder  and  the  roasting  is  properly 
managed  it  is  now  possible  to  reduce  the  litharge  to 
less  than  2  per  cent;  and  such  a  red-lead  is  so 
nearly  inactive  toward  linseed  oil  that  it  may  be 
safely  ground  in  oil  and  put  up,  like  white-lead,  in 


lO        Red-Lead  and  How  to  Use  it  in  Paint 

paste  form,  and  it  has  for  several  years  been  on  the 
market  under  the  name  of  Dutch  Boy  red-lead-in-oil. 
It  should  be  noted  that  the  name  Dutch  Boy  is  a 
trade-mark;  but  that  there  is  nothing  patentable, 
indeed,  nothing  essentially  new  or  unknown,  about 
the  manufacture  of  such  a  product;  only  proper  ma- 
chinery and  additional  care,  skill,  and  labor. 

It  will  be  observed  that  this  proprietary  name 
appears  in  the  tables  appended  to  this  book;  while 
it  is  not  intended  anywhere  to  imply  that  this  mate- 
rial is  superior  to  any  other  paste  red-lead  of  equal 
purity  and  composition,  the  fact  that  this  is,  in 
America  at  least,  the  oldest  and  best  known  make, 
and  that  it  is  composed  of  lOO  pounds  of  red-lead 
to  7  pounds  of  oil,  has  caused  the  writer  to  use  it 
as  a  standard;  the  tables  are  constructed  for  this 
mixture,  and  are  not  applicable  to  mixtures  contain- 
ing 8,  9  or  lo  pounds  of  oil  to  lOO  of  the  pig- 
ment, which  have  also  been  on  the  market.  It  was 
obviously  necessary  to  choose  some  arbitrary  stand- 
ard, to  prepare  the  tables. 


Relation  of  Lead  Pigments  to  Oil 

AH  people  who  are  experienced  In  the  use  of  paint 
agree  that  if  a  paint  is  well  applied,  in  a  workman- 
like manner,  it  will  give  better  protection  and  last 
longer  than  if  the  coating  Is  rough,  imperfect  and 
uneven.  The  study  of  paint  films  is  not  a  simple 
matter,  nor  easy,  but  some  fundamental  truths  are 


Relation  of  Lead  Pigments  to  Oil  ii 


known.  Oil  paint  consists  essentially  of  two  parts, 
the  oil  and  the  pigment.  The  pigment  is  supposed 
to  be  insoluble  in  the  oil;  but  modern  chemical  In- 
vestigations show  that  when  a  solid  and  a  liquid 
are  so  intimately  mixed,  the  solid  almost  always  dis- 
solves slightly  in  the  liquid.  Moreover,  there  is 
some  sort  of  a  surface  attraction  between  them;  the 
fact  that  a  liquid  may  adhere  with  enormous  strength 
to  a  solid  Is  shown  by  the  universal  practise  of 
lubricating  machine  bearings  with  oil;  the  shaft, 
which  Is  Itself  heavy,  Is  pulled  with  all  the  tension 
of  a  belt  down  on  the  bearing  surface,  and  yet  the 
surfaces  are  always  separated  by  a  film  of  oil  which 
cannot  be  completely  squeezed  out  even  by  the  great 
pressure,  which  Is  applied  along  a  very  narrow  strip 
of  surface,  as  the  shaft  Is  always  less  In  radius  than 
the  cylindrical  bearing  surface;  this  pressure  may 
amount  to  thousands  of  pounds  per  square  Inch. 
Just  how  far  from  the  surface  this  attraction  extends 
Is  not  known.  We  have  all  seen  the  experiments 
of  putting  the  open  end  of  a  fine  (capillary)  glass 
tube  Into  water,  when  the  water  rises  In  the  tube, 
not  from  any  chemical  action,  but  because  the  glass 
attracts  the  water;  and  if  a  similar  tube  be  put  into 
the  surface  of  mercury,  the  latter  liquid  will  appear 
to  be  repelled,  and  will  be  depressed  around  the 
glass.  It  has  long  been  known  that  wedges  of  dry 
wood  put  Into  holes  In  rocks  may  be  made  to  absorb 
water  so  that  they  will  swell  and  split  the  rock; 
this  Is  due  to  surface  attraction;  so  Is  the  shortening 
of  a  rope  when  swelled  transversely  by  wetting. 


12 


Red-Lead  and  How  to  Use  it  in  Paint 


What  is  the  cause  of  this  and  why  some  solids 
attract  some  hquids  and  not  others  is  not  known, 
but  without  doubt  these  phenomena  are  of  im- 
portance in  paints.  For  instance,  if  we  wet  red- 
lead  or  white-lead  with  water,  and  then  stir  into  the 
wet  mass  somiC  linseed  oil,  the  oil  will  be  attracted 
by  the  lead  so  much  more  than  the  water  that  the 
latter  will  be  driven  out,  rise  to  the  top  and  may  be 
poured  off,  while  the  oil  makes  an  intimate  mixture 
with  the  pigment. 

In  the  laboratory  with  which  the  writer  Is  con- 
nected there  is  at  the  time  of  this  writing  a  mixture 
of  red-lead  (98  per  cent  Pb304)  with  oil  which  was 
made  from  a  water  mixture  in  this  way,  which  now, 
after  standing  a  year,  is  a  soft,  uniform  and  com- 
plete red-lead-and-oil  paste;  and  this  method  of  pre- 
paring paste  white-lead  has  been  commercially  prac- 
tised for  many  years.  Evidently  these  pigments  have 
little  or  no  attraction  for  water;  and  these  combined 
qualities — little  affinity  for  water  and  much  for  oil — 
must  be  of  great  value  to  an  oil-paint  pigment.  No 
other  pigments  are  known  which  show  these  quali- 
ties in  so  great  a  degree;  other  pigments,  if  wet 
with  water,  must  be  dried  before  they  are  mixed 
with  oil.  We  may  extract  the  oil,  unchanged,  from 
red-lead  by  washing  it  with  ether,  which  attracts  the 
oil  more  than  the  red-lead  does;  but  there  still  re- 
mains a  little  oil,  doubtless  in  intimate  contact  with 
the  solid  surface,  which  can  only  be  removed  by 
chloroform  or  benzol,  which  attract  oil  more 
strongly  than  ether;  and  chemical  analysis  indicates 


Fineness  is  a  Merit  13 

that  a  very  little  of  the  oil  refuses  to  leave  the  lead 
even  for  these  powerful  solvents. 

Difficulty  in  Removing  Oil  from  Lead  Pastes 

The  effect  of  the  traces  of  residual  oil  on  the  sub- 
sequent analytical  process  is  so  pronounced  that  red- 
lead  of  98  per  cent  Pb304  will,  after  extraction,  ap- 
pear to  have  only  97  per  cent,  the  difference  being 
probably  due  to  the  action  of  the  minute  amount 
of  oil  present  on  the  chemical  reagents  used  ia  the 
process.  Action  of  this  sort  is  due  to  surface  at- 
traction. 

In  writing  a  specification  it  is  advisable  to  call 
for  one  or  two  per  cent  less  ^'true  red-lead''  or 
Pb304  than  is  desired,  because  of  the  fact  just  men- 
tioned. If  the  inspector  were  so  situated  that  he 
could  inspect  the  dry  pigment  before  the  oil  is  mixed 
with  it,  it  would  be  practicable  to  call  for  the  exact 
percentage  desired,  but  this  is  seldom  or  never  the 
case. 

Fineness  Is  a  Merit 

The  finer  the  pigment  the  more  surface  it  affords, 
and  the  more  strongly  does  it  act  on  the  oil,  to  bind 
the  oil  together  and  strengthen  the  film.  In  a  pig- 
ment as  fine  as  98  per  cent  PboOi  the  particles  are 
so  small  that  many  of  them,  separated  from  each 


Red- Lead  and  How  to  Use  it  in  Paint 


other  by  the  oil,  may  overlay  one  another  In  the 
thickness  of  a  paint  film,  and  such  a  film  will  neces- 
sarily be  better  than  one  in  which  the  particles  are 
coarse,  single  ones  reaching  nearly  or  quite  through 
the  whole  paint  layer,  and  separated  from  each 
other  by  bodies  of  oil  of  appreciable  magnitude. 

Also,  a  paint  like  this  will  have  a  smooth  sur- 
face, and  be  uniform  in  thickness,  and  such  a  paint 
will  be  so  much  better  than  one  made  from  low- 
grade,  coarse  red-lead  that  it  may  plausibly  be 
thought  that  its  superiority  is  due  to  its  fineness 
rather  than  to  the  comparative  absence  of  litharge. 

Makers  of  red-lead  are  generally  able  to  supply 
the  94  per  cent  grade,  and  several  companies  fur- 
nish the  higher  quality.  The  2  or  6  per  cent  not 
Pb304  is  litharge  (PbO),  which  is  residual  PbO, 
not  yet  converted  into  true  red-lead;  an  excessive 
amount  of  litharge,  say  lo  to  15  per  cent,  makes 
the  paint  diflScult  to  use,  as  it  becomes  ropy  and 
thick,  and  if  not  used  quickly  combines  with  the  oil, 
forming  a  hard  mass  in  the  container,  of  practically 
no  use  or  value.  These  low-grade  red-leads,  rated 
as  85  to  90  per  cent,  make  serviceable  paints  if 
mixed  ifi  the  field  and  used  quickly;  but  it  is  difli- 
cult  to  make  a  smooth  and  intimate  mixture,  and 
also  requires  more  than  common  skill  to  brush  it 
on  properly;  which  explains  the  engineers'  prefer- 
ence for  the  higher  grade. 

During  the  war  the  need  for  red-lead  exceeded 
the  supply.  While  a  red-lead  furnace  will  turn  out 
a  batch  of  85  or  87  per  cent  in  twelve  hours,  twice 


1 6         Red-Lead  and  How  to  Use  it  in  Paint 

this  time,  or  more,  is  taken  in  making  a  batch  of 
94  per  cent  or  over;  and  so  the  lower  grade  had  to 
be  accepted,  being  so  much  more  rapidly  made.  But 
now  the  supply  is  adequate,  and  there  is  no  reason 
why  the  former  specifications  may  not  be  insisted 
on,  greatly  to  the  convenience  and  economy  of  the 
user. 

It  is  unfortunately  true  that  in  some  cases,  during 
the  war,  a  red-lead  paint  made  with  red-lead  largely 
adulterated  (to  the  extent  of  50  per  cent  or  more) 
with  asbestine  or  silica,  was  permitted.  These  paints 
were  supplied  ground  in  oil,  and  it  was  represented 
that  they  were  stable  and  permanent  liquid  paints; 
but  at  least  one  case  is  known  where  the  buyer  at 
this  writing  has  on  hand  some  ninety  barrels  of 
such  paint  which  has  become  hard  and  solid,  and 
is  a  total  loss,  though  costing  probably  $150  or  more 
per  barrel.  The  loss  of  twelve  to  fifteen  thousand 
dollars  resulted  from  the  purchasing  agent  listening 
to  the  persuasive  words  of  the  seller,  who  was  after 
a  profit  of  five  or  six  thousand  dollars;  when  he 
might  have  bought  real  red-lead  for  probably  a 
quarter  or  a  third  more,  and  it  would  have  been 
worth  what  it  cost,  always.  And  it  would  have  been 
good  paint. 

The  buyer  should  consider  that  he  can  get  red- 
lead  and  linseed  oil  just  as  cheaply  as  anyone  else, 
and  there  is  no  advantage  in  paying  a  high  profit  on 
an  adulterated  material. 


Litharge  in  Red-Lead 


17 


Litharge  in  Red-Lead 

In  general,  it  may  be  said  that  in  painters'  red- 
lead  litharge  is  objectionable.  It  is,  however,  main- 
tained by  some  that  the  presence  of  10  or  15  per 
cent  of  litharge  is  not  harmful,  and  indeed  is  an 
advantage;  but  this  is  not  supported  by  any  argu- 
ments or  essential  facts;  so  far  as  the  writer  has 
observed,  this  is  simply  an  assertion,  unsupported  or 
nearly  so,  which  depends  for  its  effect  chiefly  on 
vociferous  reiteration.  On  the  other  hand,  it  is  now 
well  known  that  paint  made  from  85  per  cent  red- 
lead  is  quickly  discolored  when  exposed  to  the 
weather;  the  litharge  is  converted,  superficially,  at 
least,  into  carbonate,  sulphate  or  other  compound, 
while  a  similar  paint  made  with  pigment  of  98  per 
cent  PbsOi  retains  its  color  for  years,  and  is  ex- 
tensively used  as  a  signal  red,  for  which  it  is  well 
fitted  by  its  high  luminosity.  This  can  be  accounted 
for  only  by  considering  the  greater  resistance  to 
chemical  change  which  red-lead  always  shows  as 
compared  with  the  lower  oxide.  Except  for  this 
permanence  of  color,  the  question  is  not  one  of 
much  practical  importance,  for  all  admit  the  value 
of  extreme  fineness,  and  the  desirability  of  having 
a  paint  which  will  not  get  ropy  and  show  brush 
marks,  and  will  not  settle  and  separate  quickly  so 
that  part  Is  nearly  all  oil  and  another  part  nearly  all 
pigment.  These  technical  considerations  would  out- 
weigh any  minute  theoretical  advantage,  if  there 


1 8         Red-Lead  and  How  to  Use  it  in  Paint 

were  one,  in  a  paint  high  in  Htharge;  but  in  fact 
there  is  no  advantage  at  all,  except  the  slightly 
lower  price  per  pound  due  to  not  pulverizing  it 
sufficiently,  and  also  a  somewhat  reduced  price  per 
gallon,  due  to  its  greater  viscidity,  which  makes  it 
possible  to  get  brushing  consistency  with  very  little 
pigment.  This  latter  fact  is  never  put  forward  in 
its  favor,  because  everyone  knows  that  an  abnormally 
low  proportion  of  pigment  is  objectionable  in  every 
way;  nevertheless,  it  probably  has  weight  with  some 
people  whose  own  particular  interests  are  favored 
thereby. 

It  seems  to  be  only  those  who  are  opposed  to 
pure  red-lead  paint  of  any  sort  who  are  doing  this; 
and  it  may  be  that  their  object  is  to  get  all  red-lead 
into  disrepute,  so  as  to  promote  the  sale  of  some- 
thing else.  I  know,  of  course,  that  there  are  a  few 
old-timers,  especially  among  the  railway  engineers, 
who  have  excellent  master-painters,  and  well-trained 
and  disciplined  men,  who  will  use  85  to  90  per  cent 
red-lead,  mix  it  in  oil  with  much  care,  and  then 
quickly  apply  it  with  skill,  brushing  it  faithfully  and 
laboriously;  and  all  who  know  about  painting  know 
that  such  work  is  hard  to  beat,  and  is  seldom 
equalled.  But  also  it  is  seldom  seen.  What  we  are 
talking  about,  here,  is  what  happens  ordinarily.  Some 
engineers  would  keep  their  bridges  free  from  rust 
with  whitewash;  because  they  could  keep  contin- 
ually at  it.  It  does  not  matter  much  what  such 
people  use. 


How  to  Use  Litharge 


19 


How  to  Use  Litharge 

Paint  should  be  designed  for  the  purpose  for 
which  it  is  to  be  used;  and  it  would  be  foolish  to 
assume  that  there  can  be  no  place  where  litharge 
may  be  a  valuable  ingredient  in  a  paint;  but  that  is 
no  reason  why  painters'  red-lead  should  not  have  as 
high  a  proportion  of  true  red-lead  as  possible.  If 
litharge  is  desirable,  let  it  be  added  to  the  paint  as 
such,  and  let  it  be  as  finely  powdered  as  the  red-lead 
itself;  in  this  way  the  full  value  of  all  the  ingredients 
may  be  secured. 

To  give  an  example:  The  engineers  of  the  Metro- 
politan Board  of  Water  and  Sewers  in  Massachu- 
setts apply  to  the  interior  of  standpipes  and  conduits 
a  paint  made  to  contain  22.6  pounds  red-lead  of  98 
per  cent  PbsO^  in  a  gallon,  the  oil  being  a  special 
boiled  linseed  oil;  to  this  is  added  about  2.4  pounds 
powdered  litharge,  the  purpose  being  to  make  a 
paint  harder  than  pure  red-lead  because  it  is  to  be 
constantly  under  water,  and  water  tends  to  soften 
any  paint  or  varnish  film.  That  is  also  the  reason 
for  using  boiled  oil.  They  get  much  better  results 
from  this  than  by  using  a  red-lead  containing  the 
corresponding  amount  of  litharge;  partly  because  the 
paint  has  better  working  qualities,  and  also  for  some 
unexplained  reason  the  litharge  has  a  different  and 
better  effect  when  used  in  this  way.  Here  is  a 
rational  and  intelligent  use  of  this  material. 


20 


Red-Lead  and  How  to  Use  it  in  Paint 


Lampblack  in  Red-Lead 

In  like  manner  lampblack  may  be  judiciously 
added  to  red-lead.  Formerly  it  was  often  added  in 
large  quantity  to  improve  the  v/orking  quality  and 
prevent  it  from  hardening;  it  is  unnecessary  to  do 
that  now  with  high-grade  red-lead;  even  a  little 
lampblack  lessens  considerably  the  adhesion  of  red- 
lead  paint  to  iron  or  steel,  and  the  first  coat  should 
always  be  pure  red-lead;  but  it  is  an  advantage  to 
have  a  little  in  the  next  coat  to  facilitate  inspection, 
and  still  more  may  be  used  in  the  finishing  coat,  if 
the  color  thus  obtained  is  thought  desirable.  Lamp- 
black should  always  be  used  in  paste  form,  as  dry 
lampblack  is  diflScult  to  mix  with  oil;  it  has  the  high- 
est oil-taking  power  of  anything,  lampblack  paste 
containing  oil  80  per  cent  and  lampblack  20  per  cent, 
by  weight;  at  the  other  end  of  the  scale  is  red-lead 
paste,  containing  93.5  per  cent  of  red-lead  to  6.5 
per  cent  of  oil. 

It  is  sometimes  said  that  lampblack  will  not  mix 
with  red-lead;  that  it  quickly  comes  to  the  top,  and 
any  painting  done  with  such  a  mixture  is  streaky  and 
uneven.  This  is  so  if  dry  lampblack  is  used;  no 
amount  of  stirring  will  mix  It  properly,  and  It  does 
come  to  the  top.  The  reason  Is  that  It  seems  to 
stick  together  and  the  oil  does  not  penetrate  It, 
does  not  wet  It  as  water  wets  salt,  but  acts  as 
water  does  when  dry  flour  is  put  In  It;  but  if 
a  little  oil  (comparatively)  Is  put  with  the  lamp- 


Some  Things  Are  Not  Known  21 


black,  and  it  is  then  ground  through  a  mill,  it 
is  possible  to  make  a  paste  of  the  oil  and  pigment,  in 
which  (as  in  flour  paste)  every  particle  is  wet  with 
the  oil.  If,  now,  the  paste  red-lead  be  mixed  with  a 
little  more  oil,  say  a  quarter  of  its  own  volume,  and 
some  of  the  paste  lampblack  well  worked  into  it,  the 
mixture  may  be  thinned  with  more  oil  with  confidence 
that  it  will  stay  mixed.  This  is  a  general  method, 
known  to  all  good  house-painters,  for  putting  tinting- 
colors  into  paint,  but  it  is  especially  true  with  lamp- 
black, which  will  not  not  really  mix  at  all  if  it  is  put 
in  dry.  Pigments  differ  as  to  the  amount  of  oil  they 
require  to  make  pastes;  at  one  end  of  the  list  is  red- 
lead,  93^  pounds  of  which  will  mix  with  6^^  of  oil, 
and  at  the  other  extreme  is  lampblack,  two  pounds 
of  which  requires  no  less  than  eight  pounds  of  oil. 
In  using  the  latter,  remember  it  is  only  one-fifth  pig- 
ment, the  rest  being  oil. 


Some  Things  Are  Not  Knozvn 

Why  one  pigment  takes  more  oil  than  another  is 
not  known.  It  is  sometimes  said  to  be  dependent  on 
fineness,  and  in  most  cases  it  appears  to  be  true  that 
the  same  material  takes  more  oil  the  finer  it  is,  which 
is  reasonable;  but  it  does  not  hold  as  between  differ- 
ent substances;  thus,  precipitated  barium  sulphate 
takes  less  oil  than  relatively  coarse  ground  silica. 
Knowledge  in  this  line  depends  on  experimental  data. 

In  general,  the  more  oil  we  add  to  a  pigment  the 


22 


Red-Lead  and  How  to  Use  it  in  Paint 


thinner  the  paint;  and  as  spirit  of  turpentine  is  a 
more  mobile  fluid  than  oil,  we  find,  as  we  should 
expect,  that  it  thins  paint  more  than  a  like  amount 
of  oil;  but  I  think  no  one  would  suspect,  what  is  well 
known  to  all  painters,  that  a  given  measure  of  it  will 
thin  a  batch  of  paint  as  much  as  twice  as  much  oil. 

Turpentine 

The  real  use  of  turpentine  or  other  volatile 
thinner  in  paint  for  structural  steel  differs  in  some 
respects  from  its  use  in  house-painting.  In  the  first 
place,  let  it  be  said  that  the  liquid  called  benzine 
twenty-five  years  ago  has  disappeared;  it  is  too  valu- 
able in  motor  fuel  to  be  used  in  paints.  It  evaporated 
rapidly,  and  paint  or  varnish  made  with  it  would 
suddenly  stiffen  as  it  went  off,  leaving  brush-marks 
which  with  a  slower-drying  fluid  like  turpentine 
would  have  time  to  flow  out  and  become  smooth. 
The  '^mineral  turpentine"  thinners  of  today  evap- 
orate at  least  as  slowly  as  turpentine,  and  when  used 
purely  as  thinners  are  probably  just  as  good.  They 
are  inferior  to  real  turpentine  in  solvent  action;  and 
in  priming  coats  on  wood  this  is  important,  as  the 
use  of  real  turpentine  in  these  enables  the  paint  to 
penetrate  the  pitchy  surface  of  the  wood  to  some 
extent;  but  with  steel  there  can  be  no  penetration. 

In  some  cases  it  is  desirable  to  have  a  large  pro- 
portion of  pigment  in  the  paint,  and  to  secure  good 
flowing  quality  it  is  expedient  to  use,  first,  the  limited 


What  Are  Natural  Paint  Requirements? 


23 


amount  of  oil  which  is  desirable  in  the  dried  film, 
so  that  it  will  not  be  too  soft,  and  then  add  enough 
''mineral  turpentine"  to  make  it  fluid  enough  to 
brush  easily.  It  is  really  used  to  increase  the  propor- 
tion of  pigment,  or,  what  is  the  same  thing,  to 
decrease  the  proportion  of  oil,  in  the  ultimate  dried 
film  of  paint.  When  used  in  this  way  turpentine  is 
essentially  a  tool  for  the  application  of  the  paint. 
Thus,  the  Navy  specification  for  28  pounds  of  red- 
lead  (pigment)  to  a  gallon  of  vehicle  is  really  equiv- 
alent to  32  pounds  to  a  gallon  of  oil  In  the  final 
film.  Sometimes  it  is  important  to  use  turpentine  in 
this  way. 

But  in  repainting  it  is  often  a  good  thing  to  use  a 
little  real  turpentine,  to  soften  the  surface  of  the  old 
paint,  and  make  the  new  adhere  better  to  it;  and 
mineral  turps  does  not  do  this,  at  least  not  so  well. 
Mineral  turpentine  is  one  of  the  special  distillates 
made  in  the  modern  practise  of  breaking  up,  by  heat 
and  chemical  treatment,  natural  petroleum;  it  evap- 
orates completely,  not  leaving  any  greasy  residue  as 
kerosene  does,  and  has  a  nearly  constant  boiling 
point  so  that  it  all  evaporates  in  a  short  time,  say 
in  an  hour  or  so. 


W^hat  Are  Natural  Paint  Requirements? 

What  is  a  good  specification  for  a  structural 
paint?  Many  men  have  many  opinions.  In  the  first 
place,  practically  every  master-painter  will  agree 


24 


Red-Lead  and  How  to  Use  it  in  Paint 


that  different  things  may  need  to  be  painted  differ- 
ently. On  the  other  hand,  bookkeeping  in  a  large 
corporation,  such  as  a  railroad,  is  made  simpler  by 
having  as  few  formulas  as  possible;  and  a  general 
superintendent  will  very  likely  say  that  more  defects 
are  due  to  using  the  wrong  stuff  in  certain  places  than 
will  result  from  a  general-utility  formula.  Certainly 
red-lead  lends  itself  better  than  any  other  pigment  to 
such  a  formula,  but  let  us  consider  the  matter. 


Elastic-Undercoat  Cracks 

In  the  first  place,  the  more  red-lead  we  have  in  a 
gallon  the  harder  will  be  the  paint.  With  most 
pigments  more  than  a  normal  amount  is  likely  to 
cause  the  paint  to  crack  and  peel;  but  white-  and  red- 
lead  are  not  likely  to  do  that  because  of  the  remark- 
able affinity  already  spoken  of  between  the  oil  and 
the  pigment,  which  latter  is  actually  a  source  of 
strength  to  the  film.  But  it  is  a  good  general  rule 
that  successive  coats  of  paint  should  be,  progres- 
sively, more  elastic;  the  fundamental  reason  for 
which  is  that  the  sun  and  air  harden  the  oil,  and 
thus  the  outer  layer  gets  harder  than  those  beneath; 
and  if  the  undercoat  is  soft  and  the  outer  one  is 
hard,  the  latter,  not  having  a  sufficiently  firm  sup- 
port, is  liable  to  crack;  ^'an  elastic-undercoat  crack," 
the  painter  names  it.  This  is  the  most  general  cause 
of  cracks  in  paint  or  varnish.  Such  a  crack  may  not 
extend  through  to  the  foundation,  but  is  objection- 


Elastic  Undercoat  Cracks 


25 


able  in  any  case.  For  many  places  a  series  of  paints, 
made  on  the  following  plan,  would  be  satisfactory: 
priming  coat,  33  pounds  pigment  (red-lead)  to  a 
gallon  of  oil;  second  coat,  30  pounds  to  a  gallon  of 
oil;  third  coat,  28  pounds  to  a  gallon  of  oil.  But  it 
would  be  evident  that  for  under-water  work  this 
reasoning  will  not  hold;  because  exposure  to  water 
softens  the  surface,  and  it  should  be  as  hard  as  it 
may  reasonably  be;  as  has  been  said,  this  has  been 
found  to  be  like  the  priming  coat  just  described,  in 
some  cases  hardened  still  more  with  litharge.  No 
additional  coloring  matter  is  used  in  successive  coats 
in  this  case,  since  the  prevailing  opinion  among 
hydraulic  engineers  seems  to  be  that  any  such  addi- 
tions lessen  the  value  of  the  coating.  In  a  hot,  moist 
clim.ate  similar  reasoning  holds,  since  excessive 
moisture  in  warm  air  prevents  the  surface  from 
hardening  to  excess;  mildew  is  sometimes  found  on 
paint  which  contains  much  oil  in  such  regions. 

Mildew,  it  may  be  remarked,  is  a  fungous  growth, 
spread  by  spores  (which  correspond  to  seeds  of 
more  highly  developed  plants)  floating  in  the  air; 
and  the  best  preventive  appears  to  be  the  use  of  paint 
containing  a  maximum  amount  of  pigment  and  a 
minimum  of  oil,  which  becomes  too  hard  and  com- 
pact for  the  fungi  to  get  a  foothold. 

How  Much  Pigment  Is  Needed 

There  must  be  some  proportion  of  oil  and  pigment 
which  gives  most  durability.  If  too  much  oil  is 


How  Much  Pigment  Is  Needed?  27 


added,  we  finally  get  a  film  which  Is  essentially  an  oil 
film,  much  less  durable  than  a  paint,  and  less  Imper- 
vious to  air  and  moisture.  If  we  add  too  much  pig- 
ment we  make  a  paste  which,  though  fluid.  Is  too 
viscid  for  a  paint;  still  more  pigment  makes  putty, 
which  Is  not  fluid  at  all,  but  a  plastic  solid;  It  has 
uses,  but  It  Is  not  paint.  Many  years  ago  engineer- 
ing opinion  seems  to  have  settled  on  the  proportion 
of  33  pounds  of  red-lead  to  a  gallon  of  oil;  such  a 
paint  contains  22.57  pounds  of  red-lead  and  5.3 
pounds  oil  In  a  gallon.  This  proportion  Is  still  justly 
regarded  as  excellent  where  extreme  durability  Is 
required,  and  Is  used  by  several  Important  railroads; 
and  the  United  States  Navy  formula,  though  appar- 
ently on  the  basis  of  20  pounds  of  red-lead  In  a  gal- 
lon. Is  really  nearly  the  same,  because  In  the  vehicle 
there  Is  some  turpentine  and  some  turpentine  drier, 
which  are  volatile  and  raise  the  proportion  of  red- 
lead  considerably. 

The  Navy  specifications  must  not  be  confused  with 
those  of  the  Shipping  Board,  which  were  more 
loosely  drawn  and  more  laxly  enforced.  Contractors 
to  the  latter  sometimes  reported  that  they  could  not 
get  red-lead;  which  I  believe  was  never  true;  on  this 
ground  they  were  permitted  to  use  other  paints;  and 
sometimes  extreme  haste  to  finish  a  ship  caused  the 
use  of  a  red-lead  paint  made  so  that  It  would  dry 
hard  throughout  overnight. 

The  New  York  Central  Railroad  calls  for  the 
proportion  of  25  pounds  red-lead  to  a  gallon  of  oil 
for  shop  coat  (which  is  also  the  Canadian  Pacific 


28         Red-Lead  and  How  to  Use  it  in  Paint 


practise,  though  the  latter  is  said  to  be  30  pounds  to 
an  imperial  gallon,  which  comes  to  the  same  thing)  ; 
but  for  maintenance  some  of  their  engineers  use 
mixtures  as  high  as  23  pounds  in  a  gallon  including 
drier,  which  is  more  than  the  old  33  pound  formula. 
On  the  great  Hell  Gate  steel-arch  bridge,  that  dis- 
tinguished engineer,  Mr.  Lindenthal,  used  red-lead 
on  surfaces  to  be  bolted  or  field-riveted  in  the  pro- 
portion of  24^  pounds  of  red-lead  in  a  gallon  of 
paint,  or  37^  pounds  to  a  gallon  of  oil.  This  is 
practicable  only  by  using  red-lead  containing  98  per 
cent  Pb304,  which  is  both  finer  and  more  fluid  than 
the  lower  grades.  This  was  pronounced  a  satis- 
factory working  paint  by  the  painters;  and  the 
writer  has  had  a  similar  mixture  used  by  several 
painters,  at  different  times,  on  metal  gutters  and 
valleys  in  roofs,  with  excellent  results  and  the  appro- 
bation of  the  workmen. 

Twenty-five  pounds  of  red-lead  to  a  gallon  of  oil, 
or  about  18^  pounds  in  a  gallon  of  paint,  is  probably 
the  most  common  railroad  specification;  since  it  is 
unusual  for  specifications  to  be  lower  than  this,  it  is 
doubtless  below  the  average  of  specifications;  on  the 
other  hand,  shop  practise  is  to  use  much  less  in  cases 
where  the  specification  calls  only  for  a  coat  of  pure 
red-lead  paint  without  naming  the  proportion;  20 
and  even  18  pounds  to  a  gallon  of  oil  is  common,  and 
the  writer  has  known  of  as  little  as  six  pounds  of  red- 
lead  in  a  gallon  of  paint;  which  should  be  a  warning 
to  specification-writers  to  fix  the  quantity  of  pigment 
they  desire  used.    Also,  the  writer  has  known  of  a 


How  Many  Coats? 


29 


red-lead  paint  containing  about  14  pounds  of  red- 
lead  and  weighing  altogether  20  pounds  per  gallon 
which  was  used  to  fill  a  specification  calling  for  red- 
lead  paint  containing  20  pounds  of  red-lead  in  a 
gallon  of  paint;  and  this  should  be  a  warning  to 
inspectors  to  see  that  the  specification-writer's  inten- 
tions are  carried  out. 


How  Many  Coats? 

For  more  than  a  hundred  years  red-lead  has  been 
used  as  a  paint  for  iron,  and  it  has  been  known  that 
however  hard  it  may  become  with  age  it  is  never 
brittle,  and  never  scales  off  if  it  was  originally 
applied  to  the  metal,  not  to  rust  or  loose  scale;  and 
that  it  excels  most  coatings  in  adhesiveness.  But, 
as  has  been  said,  much  of  that  formerly  made  did  not 
brush  out  smoothly;  and  a  rough  surface  does  not 
wear  well;  the  grooves  and  ridges  hold  dust  and 
mud,  and  the  prominences  wear  off  by  the  abrasive 
action  of  the  weather;  it  does  not  look  well  even 
when  new,  and  worse  when  old;  the  litharge  content 
is  acted  on  by  the  carbonic  acid  in  the  air,  which 
converts  it,  superficially,  into  white-lead,  making  the 
red  color  fade  out,  and  giving  the  impression  (which 
is  not  correct)  that  the  paint  is  breaking  up  through- 
out. So  the  practise  arose  of  applying  it  as  a  first 
coat  only,  and  covering  it  with  a  couple  of  coats  of 
some  finely-ground,  easily-brushing  paint  which 
levels  the  surface,  making  it  smooth  and,  perhaps^ 


30         Red-Lead  and  How  to  Use  it  in  Paint 

glossy.  This  was  based  on  knowledge  of  the  art  and 
good  sense.  But  this  gave  rise,  not  unnaturally,  to 
the  erroneous  belief  that  red-lead  had  some  inherent 
weakness  which  unfitted  it  for  direct  exposure.  As  a 
matter  of  fact,  red-lead  is  not  less  durable,  as  a  finish- 
ing-coat, than  white-lead,  arid  probably  more  so; 
paint  made  from  paste  red-lead  is  as  finely-ground  as 
white-lead,  and  dries  with  a  smooth,  glossy  surface; 
It  has  frequently  been  said  that  it  looks,  when  new, 
as  though  varnished;  of  course,  in  a  year  or  so  the 
oil  surface  becomes  dull.  Being  almost  free  from 
litharge  the  color  is  tolerably  permanent,  enough  so 
that  it  is  largely  used  as  a  signal  red;  but  as  a  finish- 
ing coat  most  people  prefer  it  tinted  to  a  brown  or 
chocolate  color,  which  may  be  done  with  a  little 
lampblack.  There  is  really  no  reason  why  it  should 
not  be  used  for  all  three  coats;  true  economy  is 
secured  only  by  having  the  whole  of  the  film  of  the 
most  durable  material;  no  one  would  think  of  paint- 
ing a  house  with  one  or  two  coats  of  white-lead  and 
finishing  with  some  inferior  paint;  bridges  have  far 
less  surface  than  houses  of  equal  cost,  and  are  less 
durable;  they  justify  at  least  as  much  care. 

Lead  is  naturally  an  inert  metal;  it  never  rusts,  as 
iron  or  zinc  do;  it  makes  the  most  permanent  roofing 
known;  to  oxidize  it  we  have  to  melt  it  and  agitate 
it  for  a  long  time  in  the  presence  of  hot  air  in  a 
furnace;  roasting  for  two  days  and  nights  is  often 
practised  to  make  red-lead.  In  this  state  it  is  ex- 
tremely stable  to  atmospheric  action;  it  is  not  an 
electrolyte,  and  does  not  conduct  electricity;  a  dry 


The  Finishing-Coat 


31 


film  of  red-lead  paint  is  said  by  a  high  authority  to 
equal  in  this  respect  a  film  of  the  best  rubber  of  equal 
thickness.  In  so  far  as  insulation  checks  local  chemi- 
cal action,  this  is  a  good  quality  in  a  paint  for  metals. 

The  Finishing-Coat 

The  question  of  a  finishing-coat  for  metal  struc- 
tures is  one  of  considerable  interest.  There  is  no 
good  sense  in  making  it  of  readily  perishable  ma- 
terial. In  finishing  a  fine  carriage  it  has  for  a 
hundred  years  been  the  accepted  practise  to  have 
the  last  coat  of  varnish  the  most  durable  possible, 
made  of  the  best  materials,  and  costing  the  most 
money;  it  takes  the  wear;  it  is  called  in  the  trade, 
and  on  the  label,  Wearing  Body  Varnish;  and  if  it  is 
right,  it  is  the  crowning  triumph  of  the  varnish- 
maker's  art.  The  last  coat  for  house-painting  is  in 
like  manner  made  with  ultimate  care,  at  once  heavy, 
elastic  and  glossy;  the  new  apprentice  is  not  allowed 
to  put  that  on.  But,  for  reasons  already  told,  these 
principles  have  often  been  forgotten  by  the  engineer, 
who  in  this  matter  has  not  the  constant  bread-and- 
butter-earning  practise  of  the  master-painter  to 
stimulate  his  critical  observation  and  study  of  the 
problem. 

It  is  time  to  review  this  matter.  Structures  cost 
more  than  they  formerly  did;  paint  is  but  a  minute 
part  of  the  cost;  longer  life  and  safer  condition 
justify  more  care  and  expense.     In  former  times 


32         Red-Lead  and  How  to  Use  it  in  Paint 


labor  cost,  In  favorable  conditions,  at  least  as  much 
as  the  best  paint;  often  twice  as  much;  I  have  seen 
a  detailed  expense  sheet  kept  by  a  city  bridge  engi- 
neer of  long  experience  which  showed  the  cost  of  the 
paint  to  be  only  one-sixth  of  the  total  cost  of  thor- 
ough cleaning  and  repainting.  Now,  with  enor- 
mously greater  labor  cost,  and  the  paint  cost  in  less 
proportion  to  that  of  the  structure,  a  different  and 
wiser  practise  is  required. 

Highway  bridges  frequently  and  railroad  bridges 
less  often  (but  actually  in  large  numbers)  have  been 
finished  in  light  color.  The  fundamental  principles 
of  light  colored  paints  are  well  known.  In  the  first 
place,  they  are  modifications  of  white  paint;  a  light 
colored  one  cannot  be  made  from  a  dark  base.  There 
are  only  two  or  three  available  white  pigments. 
White  is  without  any  dominant  color;  and  any  white 
substance,  such  as  powdered  gypsum,  or  chalk,  if  it 
can  be  obtained  in  large  crystals,  is  seen  to  be  trans- 
parent. In  powder  they  reflect  the  light  from  their 
numerous  irregular  minute  surfaces,  and  thus  appear 
white,  as  snow  is  white  although  ice  is  clear.  If  we 
put  snow  in  water  it  loses  its  whiteness,  and  if  we  put 
a  white  pigment  into  an  oil  or  other  liquid  with 
which  it  has  similar  relations  to  light  it  is  seen  to  be 
transparent;  but  if  it  refracts  light  more  strongly 
than  the  oil  does  it  remains  white  and  opaque.  The 
principal  white  pigments  are  white-lead,  basic  lead 
sulphate  (also  known  under  a  proprietary  name  as 
sublimed  white-lead),  zinc  oxide  or  white  zinc,  and 
zinc  sulphide,  which  is  the  white  part  of  lithopone. 


34 


Red-Lead  and  How  to  Use  it  in  Paint 


Another  white  substance,  titanium  oxide,  is  appar- 
ently coming  into  use,  but  is  as  yet  too  costly  to  be 
used  pure.  Zinc  sulphide  is  not  permanent,  at  least 
for  weather  exposures,  and  may  therefore  be  left  out 
of  account.  Basic  lead  sulphate  has  never  been  used 
alone ;  it  is  a  substitute  for  white-lead  in  the  so-called 
'^ready-mixed"  house  paints,  and  seems  to  be  well 
liked  by  the  manufacturers  of  these;  but  for  a  finish- 
ing coat  over  a  dark  under-coat  it  is  not  practicable 
to  use  any  pigmentary  mixture  which  contains  a 
transparent  substance  like  silica,  silicates,  or  barytes, 
because  they  reduce  the  opacity  of  the  film.  Now, 
even  the  most  opaque  w^hite,  which  is  white-lead,  will 
not  conceal  the  under-coat  completely  if  only  one 
coat  is  applied;  red-lead,  for  instance,  will  impart  a 
reddish  or  pink  color  to  it;  and  any  more  trans- 
parent paint  v/ill  be  noticeably  worse;  as  a  general 
rule  it  will  be  found  desirable  to  depend  on  one  coat 
of  the  light  or  finishing  paint,  to  save  expense. 

Pure  white,  however,  is  not  often  desired;  and  the 
addition  of  a  very  small  amount  of  colored  pigment, 
just  enough  to  make  a  light  grey,  or  what  is  called  a 
light  stone-color,  such  as  may  be  seen  in  the  sheet  of 
color  samples  in  the  back  of  this  book,  will  so 
increase  the  opacity  of  white-lead  that  one  coat  of  it 
may  be  depended  on  to  completely  hide  a  paint  so 
brilliant  as  even  pure  red-lead.  And  the  addition  of 
this  small  amount  of  color  increases  its  durability; 
because  all  pure  white  paints  are  somewhat  trans- 
lucent, and  if  the  chemical  rays  of  the  sunlight  enter 
them  the  chemical  action  thus  set  up  tends  to  destroy 


The  Finishing-Coat 


35 


the  oil,  and  then  the  paint  wears  off.  This  is  why 
the  best  white  paint  is  less  durable  than  the  best 
colored  paint.  This  is  a  good  reason  for  using,  for 
this  purpose,  a  pure  white-lead  paint,  tinted  as  little 
as  will  produce  the  needful  opacity.  Naturally,  the 
more  transparent  the  basic  white  paint  is  the  more 
coloring  matter  it  will  require;  which  brings  another 
thing  into  consideration;  one  of  the  objects  desired  is 
that  the  paint  shall  reflect  the  sunlight  and  with  it 
the  heat;  these  are  absorbed  by  dark  paints,  and 
things  having  a  dark  color  become  hotter  in  the  hot 
sunshine  than  light  ones.  It  is  well  known,  for 
example,  that  tanks  for  volatile  oils,  such  as  gasoline 
or  motor  spirit,  are  painted  white  for  this  purpose; 
and  some  engineers  consider  that  a  bridge  which  is 
dark  in  color  will  become  hotter  and  be  subjected  to 
more  strain  from  this  cause  than  those  which  are 
light  colored.  If  this  is  a  matter  of  painting,  pure 
white-lead  is  indicated;  for  while  white  zinc  is  in 
itself  highly  opaque,  it  is  well  known  that  it  requires 
so  much  more  oil  that  it  makes  a  more  translucent 
film. 

Salesmen  sometimes  say  that  lead  paints  should 
not  be  used  around  oil  refineries  because  the  crude 
oil  contains  sulphur  which  will  permeate  the  atmos- 
phere and  attack  the  lead;  but  if  there  is  sulphur 
in  the  oil  it  is  in  chemical  combination,  and  can  be 
separated  from  it  only  by  chemical  treatment;  it  does 
not  get  into  the  air  at  all.  I  have  often  seen  in  such 
places  tanks  which  had  been  so  long  painted  with 
red-lead  that  the  linseed  oil  of  the  paint  had  weath- 


36 


Red-Lead  and  How  to  Use  it  in  Paint 


ered  off  from  the  surface  of  the  film,  and  the  litharge 
component  of  the  red-lead  had  been  converted  into 
white-lead  by  the  carbonic  acid  which  is  in  the  air, 
and  some  of  this  dry,  powdery  white-lead  could  be 
rubbed  off  by  the  hand;  but  it  remained  white,  there 
being  no  sulphur  to  attack  it.  For  all  practical  pur- 
poses the  action  of  sulphur  on  paints  may  be  left  out 
of  account,  except  in  such  extreme  cases  as  railway 
round-houses  and  enclosed  train-sheds. 


Mixed  Pigments 


The  doctrine  that  mixtures  of  pigments  are  better 
than  single  ones  is  sedulously  put  forth  by  some 
makers  of  mixed  paints  and  the  experts,  or  perhaps 
pretended  experts,  employed  by  them;  but,  while  it 
is  undoubtedly  true  that  for  certain  purposes  mix- 
tures of  pigments  are  necessary,  there  should  always 
be  a  perfectly  definite  reason  for  the  introduction  of 
each  ingredient  in  every  separate  instance,  quite  aside 
from  the  profit  it  affords  to  the  manufacturers. 
Many  of  these  fully  indorse  this  statement,  and  give 
no  support  to  the  loose  talk  indulged  in  by  others; 
they  know  by  experience  as  well  as  common  sense 
that  any  who  make  paint  on  that  plan,  and  give  the 
customer  the  best  product  their  skill  can  devise,  build 
up  a  business  on  a  sound  basis,  which  in  the  end  will 
prove  better  than  one  depending  on  alluring  adver- 
tisements. 


Good+ Worse  Is  Not  Better  37 


Good  +  Worse  Is  Not  Better 


While  no  one  should  pretend  that  the  particular 
pigment  he  fancies  is  the  only  one  which  has  any 
merit,  it  is  not  likely  that  for  durability,  or  the  pro- 
tection of  metal  from  corrosion,  a  mixture  of  pig- 
ments is  ever  better  than  a  single  one,  except  in 
cases  where  an  inferior  paint  is  improved  by  the 
addition  of  a  better  one;  that  is,  a  good  paint  is  not 
made  better  by  being  mixed  with  a  worse.  And  yet 
there  are  people  who  admit  that  silica,  for  example, 
made  by  itself  with  oil  into  a  paint,  is  worthless, 
either  as  to  durability  or  anything  else,  but  who 
maintain  that  30  or  40  per  cent  of  such  paint  may 
profitably  be  added  to  a  red-lead  paint.  They  do 
not  say  it  in  exactly  that  form :  they  say  the  paint 
may  contain  in  its  pigment  part  10  per  cent  of  silica. 
But  the  volume  of  a  pound  of  silica  is  more  than 
three  times  that  of  a  pound  of  red-lead,  and  its  oil- 
taking  power  is  higher,  and  to  make  a  paint  con- 
taining 9  pounds  of  dry  red-lead  to  i  pound  of  silica 
it  Is  necessary  to  add  to  2  gallons  of  red-lead 
paint  more  than  a  gallon  of  a  silica  paint  of  like 
consistency.  There  is  no  doubt  in  the  mind  of  the 
writer  that  such  a  paint  is  much  inferior  to  one  of 
pure  red-lead;  also  that  no  pigment  which  has 
ordinarily  been  used  in  paints  for  steel  protection 
will  improve  red-lead  for  that  purpose.  Other  things 
may  be  put  in  for  special  purposes,  as  lampblack  to 
color  it,  but  not  to  make  it  more  durable  or  better. 


38 


Red-Lead  and  How  to  Use  it  in  Paint 


V oliime  Proportions 

Probably  It  will  not  be  disputed  that  the  general 
opinion  as  to  the  composition  of  red-lead  paint 
among  engineers  is  that  33  to  25  pounds  of  this  pig- 
ment should  be  used  to  a  gallon  of  oil;  which  is 
equivalent  to  saying  that  in  a  film  of  such  paint  one- 
third  to  one-fourth  of  the  volume  of  the  film  should 
be  red-lead,  according  to  the  uses  to  which  it  is  put. 
The  effect  of  using  a  mixed  pigment  of  nine-tenths 
red-lead  and  one-tenth  silica  is  to  reduce  the  red-lead 
so  that  instead  of  a  minimum  proportion  of  one- 
fourth  it  constitutes  but  one-sixth  of  the  volume  of 
the  film;  which,  corresponding  to  15  pounds  to  a 
gallon  of  oil,  no  one  would  admit  to  be  enough; 
moreover,  the  coarse  particles  of  the  silica,  extending 
clear  through  the  film,  make  weak  places  and  danger 
spots.  Such  a  paint  will  be  offered  at  not  less  than 
nine-tenths  the  price  of  straight  red-lead  paint, 
although  it  costs  a  quarter  less  to  make;  there  lies 
the  profit,  and  the  reason  for  recommending  it. 

These  same  people  who  are  insistent  on  adulterat- 
ing red-lead  are  equally  ready  with  experimental 
proof,  of  their  own  making,  that  graphite  or  lamp- 
black are  not  only  worthless,  but  actually  induce  cor- 
rosion; but  they  also  say  that  if  these  harmful  things 
are  mixed  with  red-lead  and  small  amounts  of  two  or 
three  other  things,  according  to  methods  best  known 
to  themselves,  the  bad  qualities  of  one  are  counter- 
balanced by  those  of  another,  and  thus  their  virtues 


Simplicity  and  Complexity  39 


are  allowed  to  come  out  and  excellent  results  may  be 
expected.  The  truth  of  it  is  that  no  single-pigment 
paint  meets  their  approval;  only  such  complex  mix- 
tures as  can  be  compounded  in  a  paint  factory  and 
sold  at  a  profit,  which  increases  with  the  difficulty  of 
understanding  the  explanations. 

The  fact  is  that  loading  a  carbon  paint  with 
barytes  or  silica  is  spoiling  good  material;  some  of 
these  pure  carbon  paints  are  of  unsurpassed  dura- 
bility on  wood,  and,  while  they  do  not  answer  nearly 
as  well  on  metal,  that  is  far  from  saying  they  have 
no  merits  for  that  purpose.  The  trouble  seems  to  be 
that  they  take  too  much  oil,  and  are  thin  and  often 
do  not  adhere  well;  but  if  they  are  to  be  bodied  by 
additions,  let  something  be  used  which  has  merit  in 
itself,  even  if  it  does  add  to  the  cost.  It  is  not  well 
to  be  at  the  mercy  of  somebody  else's  purchasing 
agent,  who  may  know  the  price  of  everything  and 
the  value  of  nothing;  there  are  such. 


Simplicity  and  Complexity 

Simplicity  in  materials  is  not  always  possible,  but 
it  is  a  great  advantage,  and  in  using  red-lead  the 
best  results  are  to  be  had  by  the  least  complex 
means.  Calculations  which  involve  only  one  or  two 
pigments,  oil,  drier,  and  occasionally  turpentine, 
often  seem  sufficiently  intricate;  but  by  learning  a 
few  essential  facts  and  giving  a  little  purely  mathe- 
matical consideration  to  the  operations,  they  may  be 


40        Red-Lead  and  How  to  Use  it  in  Paint 


Simplicity  and  Complexity  4I 


mastered  by  anyone  who  cares  to  take  the  trouble. 
Indeed,  all  engineering  is  composed  of  mathematics 
and  materials;  but  the  ordinary  structural  engineer 
is  not  supposed  to  concern  himself  with  what  goes  on 
in  a  general  paint  factory,  nor  is  it  needful  that  he 
should.  The  necessary  data  will  be  given  in  another 
place,  all  together. 

Complexity  in  paints  makes  it  impossible  for  the 
average  consumer  to  understand  their  composition. 
A  paint  analysis  always  should  give,  first  of  all,  the 
weight  per  gallon;  it  never  does.  To  compute  this 
from  the  analytical  results  is  not  absolutely  impos- 
sible, but  it  is  so  to  most  people.  For  example : 
there  is  a  well-advertised  and  widely  sold  red-lead- 
and-graphite  paint,  half  the  pigment  being  repre- 
sented to  be  red-lead.  Analyses  by  disinterested  and 
capable  chemists,  running  over  a  period  of  16  years, 
show  a  sufliciently  constant  composition;  pure  linseed 
oil,  with  pigment  half  red-lead,  as  advertised.  What 
does  the  buyer  think?  He  thinks  that  he  gets  a 
paint  halfway  between  a  pure  red-lead  and  a  pure 
graphite  paint.  If  he  is  more  than  commonly  well- 
informed  he  knows  that  graphite  paints  always  con- 
tain some  of  the  natural  rock  in  which  the  graphite 
is  found;  the  graphite  paint  men  all  agree  that  a 
little  of  this,  being  well  ground  up,  improves  it  by 
giving  it  the  necessary  grit  which  the  pure  graphite 
lacks.  Maybe  it  does;  I  don't  know.  But  I  have 
my  doubts.  That  is  about  all  the  information  the 
buyer  is  likely  to  get.  If  he  knew  the  weight  per 
gallon,  he  could  multiply  It  by  the  percentages  the 


42 


Red-Lead  and  How  to  Use  it  in  Paint 


analysis  shows,  and  he  would  then  learn  that  it  con- 
tains about  5  pounds  of  red-lead,  i}4  pounds  of 
graphite  and  3^  pounds  of  '^gangue,"  nearly  all 
silica,  and  that  it  could  be  matched  by  mixing  a  quart 
of  red-lead  paint,  a  quart  of  graphite  paint,  and  two 
quarts  of  silica  paint.  That  is  considerably  different 
from  being  half-way  between  a  pure  red-lead  and 
a  pure  graphite  paint.  And  this  is  not  a  mail-order 
proposition,  nor  made  by  a  fly-by-night  concern,  but 
is  from  a  highly  reputable  and  old-established  com- 
pany; and  it  really  is  a  pretty  good  paint.  The 
reason  why  it  is  so  much  better  than  would  be 
expected  is  that  it  is  of  heavy  body;  I  myself  saw 
more  than  50  barrels  of  it  put  on  smooth,  new  steel 
plate  at  a  spreading  rate  of  325  square  feet  per 
gallon,  in  hot  weather;  taking  about  2^  times  as 
many  gallons  as  would  be  required  of  a  good  red- 
lead  paint,  and  probably  at  least  3  times  as  much 
labor.    It  ought  to  be  good. 

An  inferior  paint  spreads  over  less  surface  because 
it  is  made  of  greater  viscosity,  since  it  is  necessary  to 
have  a  thicker  film  to  get  the  required  freedom  from 
porosity  and  have  fair  wearing  quality.  With  a  free 
working  paint  of  high  durability  the  painter  can  rub 
it  out  easily  with  the  brush,  getting  better  results 
with  much  economy  of  time,  which,  with  a  high  rate 
of  wages,  reduces  the  cost  of  the  job.  Extra  re- 
paintings  are  a  squandering  of  money — not  simply 
for  the  paint,  but  still  more  for  the  labor,  which  is 
the  principal  item. 


Theory  of  Inhibition 


43 


Theory  of  Inhibition 

A  few  years  ago  there  was  a  great  outcry  about 
the  value  of  "inhibitive"  pigments.  The  theory 
involved  the  assumption  that  all  paint  coatings  are 
porous  to  water,  that  the  water  in  contact  with  the 
iron  is  ^^ionized,''  and  that  this  causes  corrosion; 
further,  that  certain  substances,  notably  salts  of 
chromic  acid,  used  as  pigments,  although  ground  in 
oil  and  the  oil  dried  into  a  solid  film,  are  still  acces- 
sible to  water,  and  although  insoluble  in  water,  as  the 
term  is  generally  used,  are  yet  slightly  dissolved,  and 
in  some  way  free  to  wander  about  the  inner  surface 
of  the  solid  and  strongly  adherent  film,  and  attack 
these  ions  of  the  water  and  put  a  stop  to  the  cor- 
rosion. When  we  consider  the  number  of  ingredients 
of  the  paint;  that  the  dried  oil  is  still  a  reducing 
agent;  that  it  always  contains  not  merely  an  appre- 
ciable amount  of  catalyzers  (driers),  but  enough  to 
make  it  dry  five  or  ten  times  as  quickly  as  pure  oil; 
that  there  is  good  reason  to  disbelieve  that  a  good 
paint  film  is  practically  permeable  to  water;  and  that 
all  this  pigment  material  is  locked  up  in  an  insoluble 
cement  of  linoxyn  or  '^oil-rubber,"  it  is  certainly 
mysterious  how  the  chromic  acid  gets  free  and  acts 
at  just  the  right  time.  It  is  no  doubt  true  that,  as 
Hamlet  said, 

"Imperious  Caesar,  dead  and  turned  to  clay, 
Might  stop  a  hole  to  keep  the  wind  away/' 


44         Red'Lead  and  How  to  Use  it  in  Paint 


yet,  as  the  conservative  Horatio  suggests,  'Twere 
to  consider  too  curiously  to  consider  so."  There  are 
too  many  improbable  things  about  this  inhibition 
process.  According  to  its  advocates,  red-lead  is  a 
material  of  no  special  merit,  but  the  Pennsylvania 
R.  R.  Co.  used  it  on  an  Ohio  river  bridge  at  Louis- 
ville, where  three  coats  when  the  bridge  was  new  and 
enough  to  make  three  more  applied  later  kept  it 
from  any  sign  of  corrosion  for  46  years,  from  1870 
to  191 6;  and  the  writer  knows  of  a  large  bridge  on 
which  the  paint,  not  containing  any  ^'inhibitive,''  but 
on  the  contrary  rich  in  ^^accelerator,"  which  was  put 
on  when  the  bridge  was  built,  has  protected  it  more 
than  twenty  years.  ^'Inhibition,"  however,  is  a 
sonorous  advertising  term,  and,  like  all  cure-alls,  is 
attractive  to  many.  The  fact  remains,  that  so  far 
as  our  experience  goes,  a  bridge  cannot  be  kept  from 
rusting  unless  we  keep  the  air  and  water  away  from 
the  metal,  and  it  will  not  rust  if  we  do.  That  is 
what  paint  is  for;  a  good  paint  does  it,  and,  on  the 
average,  a  good  red-lead  paint  does  it  longer  than 
anything  else. 

About  the  only  chemical  activity  we  are  entitled  to 
look  for  in  a  paint  film,  after  the  oil  has  dried,  is 
that  which  may  lead  to  its  destruction.  The  enthusi- 
astic seller  of  paint  sometimes  goes  so  far  as  to  tell 
that  it  will  deoxidize  rust;  also  they  talk  about  the 
pigment  being  chemically  basic,  to  neutralize  the 
acid  which  would  cause  corrosion.  No  doubt  some 
pigments  are  so;  white  zinc  is,  and  white-lead,  and 
carbonate  of  lime,  whether  In  the  form  of  whiting 


The  Havre  de  Grace  Bridge  45 


or  of  marble  dust,  and  so  is  red-lead,  and  carbonate 
of  barium  which  sometimes  takes  the  place  of 
barytes — the  substitute  for  a  substitute, — but  if  they 
were  chemically  active,  and  the  acid  could  get  into 
the  film,  how  long  would  they  last?  The  supply  of 
acid,  if  enough  to  eat  up  the  iron,  is  practically  un- 
limited. That  is  not  what  a  pigment  is  for;  we  are, 
indeed,  entitled  to  expect  it  to  be  reasonably  per- 
manent in  itself;  but  what  we  are  really  after  is  an 
impervious  film,  the  ingredients  of  which  agree 
among  themselves,  so  as  to  hold  each  other  together, 
and  be  non-porous  and  durable.  Some  one  told  the 
late  L.  L.  Buck  that  his  paint  would  penetrate  a  six- 
teenth of  an  inch  into  iron. 

**Young  man,''  said  that  old  wise  man,  '^I  wouldn't 
tell  that  if  I  were  you." 

Probably  not;  ''but,"  said  Mr.  Buck  to  me,  ''I 
shouldn't  wonder  if  some  engineers  believed  that." 
Fifteen  years  ago  a  really  capable  manufacturer 
tried  to  make  a  Portland  cement  paint;  it  is  easy 
enough  after  the  event  to  tell  why  it  did  not  work; 
but  to  this  day  we  hear,  now  and  then,  talk  of  putting 
Portland  cement  in.  That  isn't  selling  paint:  that's 
selling  psychology.  Do  not  be  flattered  into  believ- 
ing that  fourteen  weeks  in  chemistry  fourteen  years 
ago  makes  a  man  an  expert.    Go  and  see  a  chemist. 


The  Havre  de  Grace  Bridge 

In  this  connection  it  is  worthy  of  notice  that  in  the 
Havre  de  Grace  bridge  paint  test,  the  only  test  of 


46 


Red-Lead  and  How  to  Use  it  in  Paint 


paints  for  metal  designed  and  conducted  by  the 
Society  for  Testing  Materials,  none  of  the  paints 
contained  what  the  inhibition  theorists  regard  as 
inhibitory  pigments,  and  several  were  of  the  type 
supposed  to  be  most  accelerative  of  corrosion,  yet 
nearly  all  protected  the  iron,  except  from  mechanical 
injur}^,  perfectly  for  five  years,  which  absolutely 
could  not  have  been  so  if  that  theory  is  of  practical 
application;  and  at  the  end  of  the  test  after  seven  or 
eight  years,  the  best  paints  were  unmixed  red-lead, 
and  the  best  of  all  was  highest  in  Pb304  and  nearly 
free  of  PbO;  and  next  to  straight  red-lead  paints 
were  those  containing  red-lead.  After  the  test  was 
completed  this  bridge  was  repainted  throughout  with 
paint  made  from  paste  red-lead  of  high-grade,  98 
per  cent  Pb304,  twelve  years  after  its  construction. 

It  is  also  worth  noting  that,  in  the  Transactions 
of  the  American  Society  of  Civil  Engineers,  Vol. 
LXXVII,  p.  963,  an  eminent  bridge  engineer  (now 
chief  engineer  of  an  important  railroad)  gives  his 
experience  with  red-lead  containing  over  98  per  cent 
Pb304  since  1898,  showing  that  it  is  much  better  in 
all  respects  than  red-lead  of  lower  grade;  and  the 
same  engineer  is  at  the  time  of  this  writing  using  only 
this  grade  of  red-lead. 

High-Grade  Red-Lead  LLas  Been  Long  Known 

In  various  books  and  journals  of  chemistry  are 
records  of  analyses  showing  that  for  many  years 
occasional  lots  of  this  high-grade  red-lead  were 


High-Grade  Red-Lead  Has  Long  Been  Known  47 


48 


Red-Lead  and  How  to  Use  it  in  Paint 


found  in  commercial  use;  but  the  analysts  and  the 
users  are  long  since  dead,  and  no  record  remains  as 
to  what  the  material  was  used  for,  or  with  what 
results.  But  in  the  case  of  the  Louisville  bridge 
already  referred  to,  the  records  show  that  as  long 
ago  as  1870  it  was  painted  with  forty  pounds  of  red- 
lead  to  a  gallon  of  oil;  now,  if  this  had  been  the 
low-grade  red-lead  common  at  that  time,  such  a  mix- 
ture would  not  have  been  a  workable  paint,  but  more 
like  a  paste  or  putty,  owing  to  the  quick  action  of  the 
litharge  on  the  oil;  so  it  is  practically  certain  that  it 
was  high  in  true  red-lead;  such  material  was  made 
and  only  such  material  could  have  been  used;  there- 
fore, we  may  say,  it  was  used.  Mr.  Cox,  superin- 
tendent of  this  bridge,  is  authority  for  saying  that 
the  new  bridge,  which,  for  increased  weight  of 
traffic,  is  to  replace  the  old  bridge,  is  painted  with  a 
mixture  of  67  pounds  of  Dutch  Boy  red-lead  paste 
to  one  gallon  of  linseed  oil. 


Heavy  Paint 

This  paste  contains  6.54  per  cent  of  oil,  hence  67 
pounds  contain  4.38  pounds  oil  and  62.62  pounds 
red-lead;  add  i  gallon=7.75  pounds  oil,  makes 
12.13  ^^^5  ^rid  this  is  very  close  to  40  pounds  dry 
pigment  to  one  gallon  of  oil.  This  paint  had  ex- 
cellent working  quality  and  the  appearance  of  the 
painted  structure  is  extremely  good.  About  a 
hundred  thousand  pounds  of  the  paste  has  been  used 
on  this  bridge,  or  about  fifty  barrels  of  paint. 


Water  Tanks  and  Pipes  49 


Water  Tanks  and  Pipes 

It  has  been  said  that  red-lead  paint  is  used  on 
interiors  of  water  tanks,  standpipes  and  conduits. 
Twenty  or  thirty  years  ago  it  was  thought  that  this 
might  contaminate  the  water  with  lead  salts,  which 
would  occasion  lead-poisoning;  but  consideration  of 
the  fact  that  red-lead  paint  is  almost  universally  used 
on  the  outside  of  ships  suggested  the  conclusion  that 
as  the  paint  does  not  decompose,  but  remains  to  give 
good  service  for  years,  it  must  be  that  the  lead  does 
not  go  into  solution,  and  therefore  is  perfectly  safe. 
At  first  attempts  were  made  to  evade  the  question; 
to  get  the  good  qualities  the  paint  was  made  half  red- 
lead  and  half  some  other  material,  as  graphite,  and 
the  red-lead  was  reduced  still  more  in  the  finishing 
coat.  Probably  this  was  also  done  to  avoid  prejudice, 
for  there  was  much  loose  talk  about  lead-poisoning 
from  lead  water-pipes;  but  in  later  years  this  has 
been  so  completely  disproved  that  the  cities  of  New 
York  and  Boston  and  many  more  will  not  allow  any 
but  lead  pipes  to  be  laid  between  the  street  mains 
and  the  houses;  and  now  the  most  eminent  sanitary 
engineers,  such  as  those  of  the  Massachusetts  state 
organization  referred  to,  are  using  pure  red-lead  for 
all  three  coats  on  such  work.  No  lead  is  found  in  the 
water,  and  the  paint  is  quite  satisfactory. 

It  is  probable  that  in  the  future  this  well-known 
and  standard  material  will  be  more  generally  used 
for  such  purposes,  rather  than  complex  bituminous 
mixtures  of  unknown  composition,  which  cannot  be 


Red-Lead  and  How  to  Use  it  in  Paint 


Water  Tanks  and  Pipes 


51 


defined  in  a  specification  nor  analyzed  for  a  control. 
Certainly  no  paint  mixtures  of  known  composition 
can  compare  favorably  with  it. 

It  has  long  been  believed  by  observant  workmen 
that  paint  and  varnish  shrink  as  they  become  dry. 
More  than  twenty-five  years  ago  the  writer  noticed 
that  dried  raw  oil  was  heavier  than  water,  having 
increased  in  specific  gravity  more  than  could  be 
accounted  for  by  its  increase  in  weight  by  oxidation, 
which  really  is  very  little  at  the  end  of  a  year;  and 
recently  Mr.  G.  W.  Thompson,  in  a  carefully 
designed  series  of  tests,  has  shown  with  more  exact- 
ness the  amount  of  this  shrinkage.  The  practical 
application  of  this  is  that  it  probably  explains  the 
well-known  and  undoubted  tendency  to  the  appear- 
ance of  rust  on  rivet-heads  and  angles;  the  oil  first 
forms  a  skin,  and  as  this  shrinks  it  squeezes  the  more 
jelly-like,  unhardened  oil  away  from  these  prom- 
inences. To  allow  for  this,  in  a  book  published  in 
1898,  I  advised  that  after  the  first  coat  had  been 
put  on  and  had  dried,  all  rivet-  and  bolt-heads  and 
angles  should  be  specially  painted,  with  a  spotting  or 
striping  coat;  after  this  the  next  full  coat  should  be 
applied.  This  has  been  done,  not  generally,  but  at 
least  quite  extensively;  and  in  the  case  of  structures 
like  water-mains  and  pipe-lines,  which  from  their 
location  are  impossible,  or  nearly  so,  to  repaint,  this 
precaution  is  particularly  recommended. 

The  practise  of  the  hydraulic  engineers  for  the 
State  of  Massachusetts  has  been  briefly  described; 
it  is  followed  by  many  others;  recently,  in  the  case 


52         Red-Lead  and  How  to  Use  it  in  Paint 


of  some  large  water  mains,  by  the  engineers  of 
Minneapolis  and  of  Los  Angeles,  who  used  three 
coats  of  pure  red-lead.  When  the  paint  is  to  be 
exposed  to  water  it  is  not  desirable  (as  it  is  on 
bridges)  to  have  succeeding  coats  more  elastic, 
because  the  action  of  the  water  tends  to  soften  any 
paint,  and  the  surface  should  be  hard.  Boiled  lin- 
seed oil  is  advised  as  the  vehicle  in  such  cases, 
because  It  makes  a  more  varnish-like  film,  and  does 
not  hydrolize  (soften  by  the  chemical  Influence  of 
water)  as  much  as  raw  linseed  oil  sometimes  does. 

This  reasoning  also  applies  to  painting  the  outside 
of  pipes  which  are  buried  in  the  earth,  and  thus  are 
removed  from  the  action  of  sunlight;  but  unless 
these  are  In  wet  earth  they  do  not  require  boiled  oil. 
In  general,  raw  oil,  with  a  little  drier  if  necessary.  Is 
somewhat  more  durable  than  boiled  oil;  a  mixture 
of  equal  parts  of  raw  and  boiled  Is  much  used  In  all 
kinds  of  paints  where  more  than  usual  hardness  Is 
wanted. 

The  writer  recently  discussed  the  use  of  free 
litharge  with  the  principal  authority  of  the  Massa- 
chusetts board;  and  It  appears  that  after  many  years' 
experience  they  are  strongly  In  favor  of  using  red- 
lead  containing  as  little  litharge  as  possible,  and 
adding  fine  powdered  litharge  to  It  where  It  Is  to 
be  specially  resistant  to  water.  They  are  confirmed 
In  their  original  opinion  that  such  a  paint  has  ex- 
cellent working  (brushing)  qualities,  and  Is  more 
satisfactory.  This  seems  to  me  to  be  essentially  of 
the  nature  of  a  discovery. 


Boiled  Oil 


53 


Boiled  Oil 


The  reason  for  using  boiled  oil  is  that  such  oil 
partakes  of  the  nature  of  a  varnish,  and  does  not 
hydrolyze  so  readily  or  so  much  as  raw  oil;  alsi;  the 
presence  of  a  large  proportion  of  red-lead  tends  to 
prevent  that  action.  Originally,  boiled  oil  was  made 
by  putting  raw  linseed  oil  into  an  open  kettle  with  a 
proper  proportion  of  driers  and  heating  it,  with  con- 
tinual stirring,  for  several  hours  at  about  500° 
Fahrenheit.  Long  continued  heating  at  a  high  tem- 
perature causes  oil  to  dry  with  a  gloss,  like  varnish; 
such  oil  tends  to  ^'skin  over''  and  not  dry  thoroughly 
to  the  bottom,  but  this  is  remedied  to  some  extent  by 
admixture  with  a  large  proportion  of  pigment, 
especially  lead  pigments,  which  have  a  strong  affinity 
for  oil;  and  in  any  case  the  long  time  allowed  for 
drying,  as  has  been  advised,  secures  complete  hard- 
ening of  the  film.  Boiled  oil  is  commonly  made  in 
these  days  by  cooking  the  oil  and  drier  in  a  tank 
heated  by  steam  pipes;  part  of  it,  usually  20  or  25 
per  cent,  is  first  heated  with  all  the  drier  at  a  rather 
high  heat  until  the  drier  is  dissolved,  then  the  rest 
of  the  oil  is  added  and  the  whole  heated  at  a  some- 
what lower  temperature;  this  gives  an  oil  of  pale 
color,  and  generally  satisfactory;  but  for  very  exact- 
ing requirements  the  differences  in  boiled  oils  are 
considerable.  There  are  as  yet  no  recognized  and 
sufficient  specifications  for  boiled  oil,  and  a  man  must 


54 


Red-Lead  and  How  to  Use  it  in  Paint 


be  an  expert  to  judge  between  them;  judging  is  based 
on  concurrent  and  parallel  tests. 


Elevated  W ater  Tanks 


The  chief  engineer  of  one  of  the  largest  companies 
which  build  factory  water  tanks  erected  on  tall  steel 
frameworks  calls  attention  to  the  fact  that  these 
present  an  unusual  problem  in  painting.  This  is 
necessarily  left  until  the  construction  is  complete; 
then  the  working  force  goes  elsewhere,  and  one  or 
two  painters  are  left  (generally  one)  to  climb  about 
the  thing  and  paint  it  as  best  they  can.  It  has  got  to 
be  painted;  the  contract  calls  for  it;  and  it  is  imprac- 
ticable to  keep  a  dozen  high-priced  iron-workers  on 
the  job  to  occasionally  set  a  scaffold,  and  the  rest 
of  the  time  uphold  the  scenery.  There  is  the  painter, 
perhaps  a  hundred  feet  above  the  ground,  in  an 
uncomfortable  and  sometimes  dangerous-looking 
place;  generally  the  wind  blows  up  there  and  some- 
times it  is  too  cold  for  comfort;  and  he  has  no  help 
or  sympathy  from  anybody.  The  paint,  put  on  a 
cold  surface  in  the  wind,  chills  and  is  stiff ;  how  can 
he  brush  it  out  to  the  ideal  surface  the  owner  ex- 
pects? What  I  say  is,  make  the  paint  rather  thin 
with  oil,  say  the  equivalent  of  22  to  25  pounds  of 
dry  red-lead  to  the  gallon  of  oil;  and  then  thin  it 
a  little  with  mineral  turpentine,  so  it  will  flow  easily, 
more  fluid  than  you  would  use  in  ordinary  bridge 
work,  and  this  thinning  has  got  to  be  left  to  the 


Ship  Painting 


judgment  of  somebody,  either  the  painter  or  the 
inspector,  if  there  is  an  inspector,  for  it  will  vary 
from  day  to  day  according  to  the  weather.  And  it 
is  useless  to  expect  the  painter  to  use  a  very  stiff 
brush,  or  to  brush  it  very  much;  fortunately  it  is  new 
metal  and  clean.  To  make  up  for  these  conditions, 
let  the  specifications  always  call  for  at  least  three 
coats  of  pure  red-lead  paint,  tinted  to  suit;  but  if  I 
had  my  way  the  finishing  coat  should  be  white-lead, 
tinted  light  gray;  these  tall  structures  are  graceful 
and  ornamental,  at  least  to  the  engineer's  eye,  and 
should  be  made  attractive  in  color  as  they  are  always 
projected  against  the  sky;  they  naturally  keep  clean, 
and  should  look  well.  Tall  standpipes  present  much 
the  same  kind  of  a  problem. 

This  plan  involves  unusually  thin  coats  of  elastic 
paint;  the  really  right  way  to  handle  it  is  to  paint  it 
as  suggested,  and  after  one  or  two  years  give  it 
about  two  more  coats  of  the  same  sort.  By  that 
time  that  which  was  first  applied  would  be  thor- 
oughly hard,  and  no  rust  is  likely  to  have  started; 
and  with  two  more  coats  it  would  be  a  good  job. 

Ship  Painting 

Ships  are  generally  painted  with  red-lead;  for- 
merly it  was  the  practice  to  apply  three  coats,  the 
outer  being  mixed  with  white-lead  or  white  zinc;  and 
the  paint  lasted  well  even  on  the  under-water  sur- 
face.   Some  ships  and  yachts  are  now  thus  painted. 


S6 


Red-Lead  and  How  to  Use  it  in  Paint 


but  the  Navy  practise  Is  to  apply  one  coat  of  heavy 
red-lead  paint  containing,  aside  from  volatile  ingre- 
dients, to  a  gallon  of  oil  about  32  pounds  of  red- 
lead  pigment  containing  not  less  than  94  per  cent 
PbsOj,  or  if  red-lead  paste  is  the  base,  not  less  than 
97  per  cent  of  Pb304.  Over  this  is  applied,  above 
water,  a  lead-and-zinc  paint,  and  under  water  a  coat 
of  very  hard  quick-drying  varnish  paint,  and  outside 
of  this  a  similar  varnish  paint  containing  a  consider- 
able amount  of  oxide  of  mercury,  the  poisonous  effect 
of  which  hinders  the  growth  of  various  marine 
plants  and  animals  which  would  otherwise  be  at- 
tached to  the  ship's  bottom.  The  latter  two  coats 
of  paint  are  supposed  to  be  renewed  every  six 
months. 

Unless  the  red-lead  (or  any  other)  oil  paint  is 
thoroughly  dry  and  hard  before  being  put  in  the 
water  it  will  be  softened  by  continuous  soaking,  so  as 
to  be  easily  scraped  off,  even  though  it  may  still  be 
affording  protection  against  rust.  But  it  will  not  be 
thus  softened  by  water  if  it  has  become  perfectly 
dry  and  hard;  and  as  it  takes  a  year  or  more  to 
build  a  large  ship,  I  am  strongly  of  the  opinion  that 
the  best  practise  would  be  to  apply  a  coat  of  red-lead 
such  as  has  been  recently  used  on  the  Louisville 
bridge,  made  with  67  pounds  of  paste  red-lead  and 
a  gallon  of  genuine  kettle-boiled  linseed  oil;  it  would 
pay  the  shipyard  to  have  a  kettle  and  boil  their  own 
oil  if  that  is  the  only  way  to  get  it;  this  paint  should 
be  put  on  as  soon  as  the  outer  bottomplates  are  in 
place.    After  this  has  become  thoroughly  dry  and 


Ship  Painting 


57 


hard  a  second  similar  coat  should  be  put  on  the 
under-water  part,  but  above  the  water-line  the 
amount  of  red-lead  paste  should  be  reduced  to,  say, 
58  pounds  to  a  gallon  of  oil;  this  should  be  allowed 
time  to  become  thoroughly  dry;  then  a  third  coat,  the 
same  for  the  bottom,  but  only  50  pounds  of  paste 
to  the  gallon;  and  I  think  for  this  last  above-water 
portion  I  should  prefer  half  boiled  and  half  raw  oil. 
Sixty-seven  pounds  of  paste  to  a  gallon  of  oil  cor- 
responds to  about  40  pounds  of  pigment  to  a  gallon; 
58  pounds  to  about  36  or  37  pounds  of  dry  red-lead 
to  a  gallon,  and  50  pounds  to  33  to  a  gallon  of  oil. 
These  high  proportions  would  be  impracticable  with 
red-lead  of  less  than  97  or  98  per  cent  Pb304;  but 
it  seems  to  me  that  the  results  obtained  by  the  engi- 
neers of  the  Massachusetts  water  supply  commission, 
and  the  forty-six  years'  test  on  the  old  Louisville 
bridge,  justify  such  practise,  which,  moreover,  agrees 
with  the  author's  long  experience. 

I  am  certain  that  any  bridge  engineer  will  agree 
that  a  ship — which  is  a  steel  structure — painted  as 
described  would  be  well  painted;  and  it  would  be 
reasonably  sure  to  remain  in  good  condition  for 
many  years.  It  may  be  true  that  the  best  of  paint 
will  get  scraped  off;  but  the  surface  actually  bared  in 
this  way  is  a  small  proportion  of  the  total  surface, 
and  if  this  is  promptly  and  carefully  spot-painted 
with  a  red-lead  paint  which  has  been  made  quick- 
drying  by  a  more  than  usual  amount  of  drier,  no 
serious  corrosion  should  ever  occur.  Because  a  ship 
offers  a  different  problem  of  protection  than  a  bridge 


Ship  Painting 


59 


Is  no  reason  why  the  constructor  should  ^'lie  down" 
and  give  It  up  as  a  hopeless  job ;  a  big  railroad  bridge 
costs  It  may  be  half  a  million  to  a  million  dollars, 
and  the  engineer  spends  much  more  money  on  Its 
painting  than  Is  here  proposed  for  a  ship  costing  ten 
millions,  or  more. 

The  whole  tendency  of  late  years  seems  to  have 
been  to  shunt  off  the  responsibility  for  maintenance 
from  the  naval  architect  on  to  the  captain  or  the 
owner.  Of  course  the  latter  should  realize  their 
responsibilities,  but  it  is  more  weightily  true  of  a 
ship  than  of  other  structures  that  the  one  best  time 
for  painting  is  during  construction,  when  it  is  under 
shelter,  and  the  metal  is  new  and  clean,  and  time  and 
opportunity  are  practically  unlimited.  If  a  railroad 
engineer  had  a  big  bridge  under  a  roof  for  a  year  he 
would  do  something  to  it  besides  putting  on  one  coat 
of  paint.  After  the  three  coats  of  red-lead  as 
described  there  should  be  one  coat  (above  the  water- 
line)  of  half  red-  and  half  white-lead;  to  lOO  pounds 
of  the  mixed  paste  add  a  gallon  and  a  half  of  raw 
oil,  a  gallon  and  a  half  of  turpentine,  and  a  pint  of 
drier;  then  a  coat  of  color  over  this.  These  will  dry 
quickly.  Some  day,  I  hope,  some  ships  will  be 
painted  this  way;  and  when  they  are  the  shipyard 
will  cease  to  be  a  place  besieged  by  every  paint  quack 
from  this  country  and  abroad. 

It  may  be  said  that  such  elaborate  painting  is 
evidently  designed  for  a  permanent  structure,  while 
a  battle-ship  becomes  obsolete  in  fifteen  or  twenty 
years.    It  is  not  designed  to  be  so;  and  If  proper 


6o 


Red-Lead  and  How  to  Use  it  in  Paint 


painting  will  prevent  corrosion  it  will  aid  greatly  in 
maintaining  the  speed,  which  is  highly  desirable.  I 
have  seen  a  ship-of-war  cleaned  with  sand  blast, 
which  revealed  rust-pits  on  the  sides,  below  the 
water-line,  large  enough  to  hold  peas;  objectionable 
in  themselves  and  affording  hold  for  marine  plants 
and  animals.  When  premiums  were  given  for  speed, 
the  growth  of  such  things  on  the  bottom  of  a  new 
ship  In  two  weeks  was  enough  to  cost  the  builders  a 
hundred  thousand  dollars.  It  is  likely  that  for  the 
money  spent  nothing  Increases  the  value  of  a  ship 
so  much  as  good  paint  on  the  bottom.  No  doubt  an 
anti-fouling  paint  Is  also  needed,  but  there  should  be 
a  smooth,  clean  surface  on  which  to  put  it. 


Railway  Cars  and  Other  Vehicles 

Steel  railway  cars,  especially  coal-cars  and  others 
having  the  upper  or  container  parts  of  sheet  metal, 
have  often  been  neglected  in  the  past.  Some  of  the 
best  railways  have  long  painted  these  with  at  least 
one  coat  of  red-lead;  but  others  have  allowed  the 
use  of  very  cheap  and  inferior  paints,  claiming  that 
any  paint  is  quickly  abraded  and  Is  of  little  use.  But 
during  the  war  the  impossibility  of  getting  enough 
cars,  and  later  their  high  prices,  gave  new  weight  to 
the  claims,  of  those  who  painted  them  well,  that 
their  cars  lasted  longer.  They  certainly  do;  one 
never  sees  a  car  which  has  been  well  painted  looking 
so  dilapidated  and  generally  disreputable  as  those 


Railway  Cars  and  Other  Vehicles  6: 


which  were  neglected  in  the  first  place.  No  doubt 
dumping  coal,  or  broken  stone  for  concrete,  scratches 
off  some  of  the  paint;  but  does  any  one  stop  to  think 
how  long  it  would  take  to  get  all  the  paint  off  in  that 
way  if  we  wanted  to  remove  it?  Especially  on  the 
outside;  it  cannot  be  done.  Small  spots  of  metal 
may  show;  but  it  would  take  quite  a  gang  of  men  to 
clean  all  the  paint  off  a  coal  car  in  a  week,  with 
scrapers.  Such  paint  does  not  flake  oft  ;  every  in- 
dividual particle  has  to  be  scraped  off.  What 
destroys  a  steel  car  is  having  the  whole  surface  get 
rusty,  so  that  it  becomes  thin  in  large  areas  and 
breaks  away.  If  cars  were  well  painted  when  new, 
and  repainted  once  in  five  or  six  years,  the  bodies 
would  last  until  the  running  parts  wore  out.  And 
the  running  parts,  or  gear  as  wagon-builders  call 
them,  will  repay  good  painting.  The  metal  parts  of 
street  cars  generally  are  so  painted,  and  ought  to  be 
always. 

This  leads  to  consideration  of  wagons  and,  espe- 
cially, automobiles.  It  is  not  uncommon  to  see  paint 
scale  off  in  large  flakes;  it  needs  a  good  priming  coat 
to  stick  to  smooth  metal,  especially  if  the  latter  is 
subject  to  vibration  and  shock.  The  hard  varnish, 
often  baked  on,  which  is  the  outside  finish,  tends  to 
crack  and  pull  off  the  undercoat,  and  the  latter  should 
be  such  as  will  adhere  to  the  metal  with  the  greatest 
obstinacy  and  it  is  generally  conceded  that  nothing 
equals  red-lead  in  this  respect.  It  may  be  used,  if 
so  wished,  with  a  spraying-machine;  the  Navy  De- 
partment painters  have  painted  the  outside  of  ships 


62 


Red-Lead  and  How  to  Use  it  in  Paint 


in  this  way,  using  exactly  the  same  mixture  as  for  the 
brush.  Formerly  this  was  thought  impossible,  and 
there  are  now  some  machines  which  will  spray  only 
thin  paints,  but  with  the  proper  device  lead  paints  can 
be  sprayed.  But  most  people  prefer  the  brush.  At 
least  two  coats  of  red-lead  should  be  used,  so  as  to 
get  a  good,  solid  film;  the  car  painter  often  finishes 
with  a  coat  of  cheap  black  paint,  to  show  up  the 
lettering  which  is  done  with  white-lead,  no  other 
white  paint  being  sufficiently  opaque ;  but  it  would  do 
the  railway  men  good  to  consider  the  practice  of  the 
builders  of  farm  wagons.  It  is  important,  as  a  mat- 
ter of  advertising  to  the  wagon-builders,  to  have 
these  remain  well  painted  as  long  as  possible;  hence 
they  use  as  good  paint  as  they  can  get  for  the  finish- 
ing coat,  and  it  lasts  well.  Why  not  paint  cars  on 
this  plan;  if  the  finishing  coat  lasts,  and  the  under- 
coats do  not  come  off,  the  owner  will  be  the  gainer. 
Cars  are  going  to  cost  more  money  than  they  have 
in  the  past,  and  it  will  be  a  more  serious  thing  to  let 
them  be  destroyed  by  neglect.  There  is  no  more 
sense  in  it  than  there  would  be  in  neglecting  to  paint 
a  bridge. 


How  to  Test  Red-Lead  Paint 

Inspection  of  red-lead  paint  by  weight  is  very  easy 
and  the  inspector  should  know  how  to  do  it.  A  gal- 
lon of  water  weighs  8.33  pounds;  hence  any  pail 
which  holds  that  amount  of  water  may  be  used  as  a 


How  to  Test  Red-Lead  Paint 


63 


gallon  measure.  A  table  appended  to  this  book  gives 
the  weight  per  gallon  of  practically  every  sort  of  red- 
lead  paint.  The  inspector  can  weigh  a  gallon  of  it 
on  any  ordinary  scale  to  an  accuracy  of  i  per  cent 
which  would  be  about  a  quarter  of  a  pound,  which 
tells  at  once  if  it  is  near  the  specification.  A  gallon 
of  good  red-lead  paint  weighs  over  23  pounds. 

It  takes  but  a  few  minutes  to  make  a  test,  any- 
where. A  fair  sample  must  be  taken.  As  red-lead 
is  the  heaviest  pigment,  any  adulteration  will  show 
lessening  of  weight.  This  is  in  fact  an  argument  in 
favor  of  red-lead — it  is  so  easy  to  inspect;  and  a 
similar  reason  may  be  urged  for  using  paste  red-lead, 
100  pounds  of  which  measures  but  2^  gallons  and 
is  the  smallest  100-pound  package  ever  seen  in  the 
paint  trade;  an  adulterated  material  requires  a 
package  so  much  larger  as  to  be  easily  noticed;  and 
the  pigment  must  contain  at  least  97  per  cent  PbsOi 
or  it  would  harden  in  the  container,  and  the  maker 
would  not  venture  to  put  it  up;  and  it  must  be  fine, 
because  it  cannot  be  oxidized  to  97  per  cent  unless 
it  is  extremely  and  uniformly  so. 

The  only  thing  to  test  is  the  oil,  a  sample  of  which 
may  be  dissolved  out  with  ether.  If  it  smells  and 
dries  like  linseed  oil  it  is  pretty  sure  to  be  linseed  oil; 
the  only  adulteration  the  writer  has  met  with  in  oil 
in  paste  red-lead  Is  a  fish-oil  soap,  which  has  an  evil 
odor,  and  the  extracted  oil  does  not  dry  properly. 
So  the  only  test  necessary  requires  no  laboratory  or 
much  apparatus,  or  any  training,  more  than  any 
young  engineer  may  be  expected  to  have. 


64         Red-Lead  and  How  to  Use  it  in  Paint 


Advantages  of  Paste  Red-Lead 

Dry  red-lead  is  not  so  easy  to  distinguish;  Its 
weight  per  cubic  Inch  may  vary  100  per  cent  and 
adulteration  may  be  difficult  to  determine.  But  the 
more  Important  reasons  for  using  paste  red-lead  are 
Its  fineness,  smoothness  and  ease  of  working,  uni- 
form thickness  of  film  and  consequent  economy,  and 
its  sanitary  advantage;  as  It  Is  free  from  dust  It 
never  causes  lead  poisoning. 


Sanitation 

The  class  of  workmen  who  generally  use  red-lead 
are  not  aware  of  the  danger  from  the  dry  powder, 
which  Is  appreciable,  and  their  employers  should  take 
all  expedient  precautions  for  their  protection.  This 
is  not  an  Individual  fad  of  the  v/rlter;  white-lead, 
formerly  used  dry.  Is  now  almost  exclusively  sold  as 
paste  ;  some  large  and  Important  paint  manufacturers, 
as  Masury  &  Co.,  and  the  Lowe  Bros.  Co.  (others 
might  be  named),  will  not  use  It  dry  because  of  the 
danger  to  their  employees ;  a  single  one  of  the  numer- 
ous lead-products  makers  has  spent  more  than  two 
hundred  thousand  dollars  In  protecting  the  workmen 
from  such  dust;  and  certainly  the  buyers  of  red-lead, 
some  of  whom  buy  a  hundred  tons  at  a  time,  may  be 
invited  to  give  the  matter  a  little  consideration. 


Lower  part,  rust  lumps,  or  "tubercles";  Xi-    Above,  part  of  the  same 
surface,  sand-blasted,  showing  pitting 


66 


Red-Lead  and  How  to  Use  it  in  Paint 


Need  of  Cleaning 

This  book  is  primarily  about  red-lead  painting; 
but  no  book  should  ever  be  written  about  painting  on 
metal  without  saying  something  about  cleaning  the 
metal  surface;  this  is  the  foundation,  and  the  source 
of  most  of  our  troubles.  Any  decent  paint  on  a  per- 
fectly good  surface  will  outlast  the  best  possible 
paint  on  a  poor  one.    That  is,  paint  is  not  fool-proof. 

The  fundamental  proposition  is  that  paint  sticks 
to  iron  in  the  same  way  that  other  things  do.  We 
know  how  other  things  do.  Thus :  if  the  electro- 
plater  wishes  to  deposit  copper  or  nickel  on  iron, 
he  cleans  it  first;  scrapes  off  any  coarse  dirt,  then 
puts  it  in  an  acid  bath  and  cleans  off  all  dirt,  oxide 
and  scale,  leaving  the  metal  with  its  own  gray-white 
color  to  be  seen  in  all  parts.  Then  he  expects  to 
be  able  to  secure  perfect  adhesion  of  his  coating. 
Those  who  apply  vitreous  glazes,  as  with  granite- 
ware  and  the  like,  do  the  same  thing;  and  varnish 
enamels  require  the  same  surface.  In  all  these  cases 
it  is  perfectly  well  known  that  no  dirt  nor  grease 
nor  intermediate  film  of  any  kind  may  be  allowed 
between  the  actual  metallic  surface  and  the  coat- 
ing; otherwise  the  latter  will  crack  and  peel  off. 
Paint  is  softer  and  tougher  and  does  not  crack  so 
easily;  and  it  yields  more  to  expansion  and  contrac- 
tion from  changes  of  temperature.  Sometimes  it 
protects  the  film  of  scale  so  that  the  latter  does 
'not  come  off  as  easily  as  it  otherwise  would,  and 


Sand  Blast 


67 


In  this  way  it  remains  in  place  and  protects  the 
metal  beneath;  but  perfect  adhesion  is  possible  only 
where  it  touches  the  bare  metal.  The  only  common 
method  of  getting  this  condition  is  by  using  the 
sand  blast. 


Sand  Blast 

The  writer  was  the  first  to  use  this  method  on 
structural  metal  (see  Engineering  News,  Sept.  23, 
1897,  or  Engineering  Record,  Sept.  25,  1897), 
which  has  now  come  into  common  use;  though  I 
suppose  not  more  than  i  per  cent  of  all  structural 
steel  is  ever  cleaned  in  this  way  even  now.  Several 
railroad  companies  have  sand-blast  plants  mounted 
on  cars  for  cleaning  bridges  in  place;  and  it  would 
be  an  excellent  investment  if  every  state  highway 
commission  had  one  mounted  on  a  truck  which  could 
be  shipped  by  rail  to  a  convenient  point  and  then 
hauled  to  the  bridge;  as  the  railway  companies  are 
heavy  tax-payers  they  might  be  willing  to  give  free 
transportation.  Sand,  which  is  sometimes  the  chief 
item  of  expense,  is  generally  cheap  in  the  country. 
I  have  known  a  railway  company  to  furnish  men 
and  apparatus  to  sand-blast  highway  bridges  for 
the  mere  cost  of  labor  of  the  men  employed.  High- 
way engineers  should  always  cultivate  the  friend- 
ship of  the  railroad  men;  both  will  be  gainers  by  it. 

The  details  of  this  method  are  so  well  known  that 
it  is  not  worth  while  to  describe  them,  and  informa- 


68 


Red-Lead  and  How  to  Use  it  in  Paint 


tion  may  be  had  from  the  numerous  makers  of 
machines  who  advertise  in  the  engineering  papers. 
In  a  general  way  it  may  be  said  that  the  tendency 
seems  to  be  to  use  higher  air  pressure  and  smaller 
hose  than  formerly,  80-  and  even  100-pound  pres- 
sure per  square  inch  being  often  used;  high  pressure 
is  necessary  to  cut  away  hard  scale.  The  cost  seems 
to  be  from  two  to  five  cents  per  square  foot,  vary- 
ing with  cost  of  sand,  staging,  cleaning  up  of  debris, 
and  the  size  of  the  job.  The  nozzle-men  should 
always  wear  dust-proof  helmets,  as  the  powdered 
sand  is  very  injurious  to  the  lungs.  It  should  never 
be  used  in  a  confined  space  unless  so  situated  that  it 
may  be  constantly  swept  by  an  abundant  current  of 
air;  otherwise  the  paint  dust  may  cause  harm. 


Pickling 


Metal  surfaces  may  also  be  cleaned  by  pickling, 
which  is  by  immersing  them  in  a  dilute  acid — com- 
monly sulphuric— until  the  scale  has  dissolved  or 
has  fallen  off  because  the  acid  has  penetrated  be- 
neath it.  This  process  was  used  for  cleaning  the 
anchorage  of  the  old  Brooklyn  Bridge;  and  the 
steel  underfloor  of  the  Williamsburg  Bridge;  also 
for  pipes  to  be  enameled,  for  United  States  ships; 
but  otherwise  it  has  been  used  little  or  not  at  all 
on  structural  material  in  this  country.  It  has  long 
been  used  in  England  and  Europe  on  bridge  material 
and  the  like.    It  is  said  by  experts  of  the  Western 


Pickling 


69 


Electric  Company,  which  does  great  quantities  of 
enameling,  that  it  produces  a  better  surface  than  the 
sand  blast.  The  pickled  surface  is  full  of  sharp 
points,  holes,  ridges  and  furrows,  to  which  the  coat- 
ing adheres;  while  the  sand-blasted  surface  is 
smooth,  the  prominences  and  depressions  being 
rounded,  smooth,  and  possibly  slippery. 

Before  pickling  the  pieces  are  soaked  in  hot  10 
per  cent  caustic  soda  solution,  to  remove  grease  and 
dirt,  then  washed  and  put  in  the  dilute  acid  which 
sometimes — perhaps  usually — is  about  10  per  cent 
acid;  it  is  kept  hot  by  blowing  steam  into  it.  It  is 
left  in  this  until  the  whole  surface  is  clean;  the  time 
will  depend  on  its  condition.  It  is  also  good  practise 
to  use  stronger  acid,  20  to  28  per  cent,  also  hot, 
which  will  clean  the  metal  in  five  to  ten  minutes. 
It  is  not  absolutely  necessary  to  use  the  preliminary 
alkali  bath;  but  it  has  the  effect  of  keeping  the  acid 
bath  cleaner. 

On  removal  from  the  bath  the  acid  must  be  re- 
moved. This  may  be  done  in  any  of  several  ways. 
In  some  large  plants  the  metal  is  washed  in  boiling 
water,  then  in  10  per  cent  carbonate  of  soda  solu- 
tion, then  again  in  hot  water.  If  the  metal  is  first 
put  into  cold  water  from  the  acid  a  gummy,  colloidal 
basic  sulphate  is  formed,  difficult  to  remove;  but 
it  may  be  washed  with  a  jet  of  water  from  a  hose, 
at  a  pressure  of  not  less  than  100  pounds  per  square 
inch,  which  mechanically  cleans  the  surface.  Others 
practise  putting  it  from  the  acid  into  hot  milk  of 
lime  (made  by  stirring  freshly  slacked  lime  in  water) 


70 


Red-Lead  and  How  to  Use  it  in  Paint 


and  after  removing  it  let  it  dry,  and  before  painting 
brush  off  the  lime  dust.  This  is  a  simple  and  ex- 
cellent way,  the  more  so  as  iron  thus  treated  is  not 
likely  to  rust  until  the  lime  is  brushed  off.  The  cost 
of  pickling  moderately  heavy  structural  shapes  is 
probably  about  $i.oo  a  ton;  but  little  is  accurately 
known  about  this  part  of  it,  in  this  country. 

Scraping  and  JVire-briishing 

Comparatively  little  structural  metal  is  cleaned  by 
such  thorough  methods  as  have  been  described;  the 
next  best  way  is  by  scraping  and  wire-brushing.  The 
wire  brush  alone  is  not  good  for  much  but  it  is  good 
to  clean  off  loose  dirt.  Sometimes  it  is  necessary 
to  use  a  hammer  and  chisel  to  get  oif  thick  and 
closely-adherent  scale;  but  scrapers  are  usually  de- 
pended on;  these  are  strongly  made  of  tool  steel, 
often  with  substantial  wooden  handles;  of  various 
sizes  and  widths,  so  as  to  get  into  recesses.  Some 
are  bent  at  right  angles  near  the  end  and  are  used 
like  a  hoe. 


Mill-scale 

In  any  case  it  is  necessary  in  some  way  to  get  rid 
of  rust.  The  closely  adherent  blue  mill-scale  is 
anhydrous,  and  in  itself  is  not  so  bad;  it  is  true  that 
in  the  presence  of  acid  or  perhaps  water  it  acts  as 


Rust  is  Persistent  and  Obstinate  71 


an  electrode,  setting  up  chemical  action;  but  the 
universal  experience  of  practical  painters  is  that 
closely  adherent  clean  blue  mill-scale  does  not  cause 
trouble  if  well  painted.  This  is  regarded  as  rank 
heresy  and  impossible  by  some  of  the  more  unbend- 
ing theorists,  but  if  it  is  true  it  is  probably  because 
it  ought  to  be  so.  The  writer  has  seen,  after  re- 
moval of  the  paint,  sound  and  continuous  blue  scale 
on  sheets  of  iron  (pipe)  which  had  been  buried 
in  clay  for  twenty  years.  Nevertheless,  it  is  safer 
to  get  it  off  if  it  will  come  off ;  any  scale  which  is  at 
all  loose  is  dangerous. 


Rust  Is  Persistent  and  Obstinate 


It  is  well  known  to  most  people  that  iron  exists 
in  nature  chiefly  as  oxide;  sometimes  it  occurs  in 
meteorites  (perhaps  only  there)  in  the  metallic 
state;  but  practically  all  terrestrial  iron  is  in  chemical 
combination.  To  extract  the  oxygen  from  the  oxide 
we  mix  it  with  coke  or  charcoal,  and  in  the  intense 
white  heat  of  the  blast  furnace  the  carbon,  in  a 
gaseous  form,  burns  out  the  oxygen,  and  the  iron 
runs  out  as  a  liquid.  But  nature  is  always  trying 
to  get  it  back  into  an  oxide,  and  sooner  or  later 
this  will  come  to  pass;  all  we  can  do  is  to  retard 
the  process  as  much  as  we  can,  which  is  by  keeping 
oxygen  away  from  it  with  paint,  concrete,  and 
similar  means.  The  oxide  may  be  anhydrous,  as 
hematite,  magnetite,  or  the  blue  scale  formed  in  the 


72         Red-Lead  and  How  to  Use  it  in  Paint 


Rust  on  a  neglected  highway  bridge 


Rust  is  Persistent  and  Obstinate  73 


rolling-mill;  or,  more  commonly,  hydrate,  as  the 
mineral  limonlte,  or  as  common  rust.  This  cannot 
be  dehydrated,  in  the  chemical  sense,  except  by  a 
protracted  red  heat;  though  free  absorbed  moisture 
may  probably  be  driven  out  by  a  somewhat  pro- 
longed use  of  the  painter's  torch.  Rust  is  an  ob- 
stinate and  obnoxious  thing;  even  when  it  looks  dry 
it  generally  holds  moisture,  and  the  moisture  holds 
carbonic  acid;  these  act  on  the  metal  and  make  more 
rust,  which  swells  and  makes  cracks  in  the  paint,  and 
from  the  air  the  supply  of  oxygen  is  renewed;  so 
it  is  that  ''rust  doth  corrupt."  It  is  not  to  be 
tolerated. 

Smeaton,  of  whom  James  Watt  said  that  ''his 
example  and  precepts  have  made  us  all  engineers," 
said  he  "had  observed  that  when  iron  once  gets 
rust,  so  as  to  form  a  scale,  whatever  coat  of  paint 
or  varnish  is  put  on  over  this,  the  rust  will  go  on 
progressively  under  the  paint."  The  following 
century  and  a  half  of  observation  has  made  no 
change  in  the  truth  of  this,  which  is  only  confirmed 
by  longer  experience.  Not  that  paint  does  no  good 
unless  applied  to  a  perfect  surface;  if  it  is  a  good 
paint  it  obstructs  and  retards  the  entrance  of  air 
and  moisture;  but  it  is  important  to  get  as  clean 
metal  as  possible.  The  difficulty  of  doing  this  gives 
rise  to  all  sorts  of  illusions;  it  has  already  been  told 
how  scientific  terms  have  been  misused  in  this  way; 
and  all  kinds  of  extravagant  claims  are  persistently 
and  persuasively  urged.  Only  the  other  day  (so  to 
speak),  a  well-known  engineer  in  responsible  charge 


74         Red- Lead  and  How  to  Use  it  in  Paint 


of  an  important  bridge,  applied  to  it  a  certain  paint 
which,  he  said,  experience  for  several  years  had 
shown  to  '^absorb  the  oxygen  from  rust";  as  the 
chief  chemist  of  one  of  the  big  steel  companies  said, 
"thus  doing  away  with  the  blast  furnace."  Another 
chemist  suggested  that  it  was  a  new  catalyzer;  still 
another  (a  paint  chemist)  that  the  salesman  was  a 
psychologic  catalyst,  the  exuberance  and  vitality  of 
whose  fancy  delights  and  deludes  those  who  have 
never  lived  in  his  world  of  imagination. 


Brushes 


Good  painting  requires  good  brushes.  Most 
painters  advise  the  use  of  what  is  called  a  pound 
brush;  the  bristles  when  new  are  about  six  inches 
long,  and  the  shape  is  cylindrical.  Bristles  of  this 
length  are  too  flexible;  so  it  is  customary  to  "bridle" 
the  brush,  which  is  to  confine  it  so  that  only  the  tip 
of  it  is  used,  the  part  nearer  the  handle  being  tied 
so  as  to  be  a  solid  mass.  This  is  done  in  various 
ways :  a  bridle  may  be  bought  from  the  brush-maker; 
or,  with  a  long  cord,  the  brush  may  be  wound  from 
a  suitable  place,  say  2  or  2^  inches  from  the  bind- 
ing, to  completely  bind  the  brush  to  where  the  brush- 
maker's  binding  begins;  or  a  strip  of  cloth,  about 
8  inches  wide,  may  be  wrapped  around  the  brush 
and  securely  tied  to  the  binding.  Then  with  another 
piece  of  cord  tie  it  around  the  bristles,  say  4  inches 
from  the  end  of  the  bristles  and  2  inches  from  the 


Brushes 


75 


binding;  then  turn  back  the  cloth,  like  a  sleeve  turned 
half  inside  out,  and  tie  it  again  around  the  binding. 
Trim  it  off,  and  the  bridle  is  done.  As  the  bristles 
wear  off  the  bridle  may  be  moved  up,  and  finally 
removed.  But  do  not  buy  a  new  brush  with  a  bridle 
on  it;  take  it  off  and  see  that  the  bristles  are  elastic 
and  strong;  soft  flabby  bristles  do  not  make  a  good 
brush. 

A  new  bristle  naturally  terminates  with  what  is 
sometimes  called  a  feather;  split  up,  as  it  were,  into 
fibers.  These  hold  the  paint;  and  there  should  be 
shorter  bristles,  with  these  ends,  all  through  the 
brush,  so  that  as  it  wears  off  it  will  still  have  this 
necessary  quality.  The  object  of  binding  is  to  pre- 
vent the  brush  from  being  too  soft,  and  spreading 
like  a  mop;  it  is  supposed  to  rub  the  paint  into  the 
rough  surface  of  the  iron,  and  to  rub  out  the  air 
film  which  adheres  to  the  surface;  air,  and  probably 
an  invisible  coat  of  moisture,  adhere  strongly  to  a 
metal  surface.  This  is  one  reason  why  many  prefer 
the  brush  to  the  spraying-machine. 

If  flat  brushes  are  used  they  should  not  be  more 
than  4  inches  wide,  or  5  at  the  most,  for  metal 
painting;  and  they  should  be  good  thick  brushes, 
of  good  material.  Using  a  wider  brush  it  is  im- 
possible to  rub  out  the  paint  properly. 

Brushes  used  in  oil  paints  may  be  kept  fresh  and 
clean  overnight,  or  while  carrying  them  from  place 
to  place,  by  wrapping  them  closely  in  several  thick- 
nesses of  paper;  It  is  better  if  the  Inner  layer  of 
paper  be  wet  with  water. 


76 


Red-Lead  and  How  to  Use  it  in  Paint 


When  through  with  a  job  they  may  be  well  washed 
out  with  kerosene,  and  then  well  rinsed  with  gasoline, 
and  hung  up  to  dry  where  they  will  be  free  from 
dust. 

Brushes  which  are  worn  short,  so  as  to  be  stiff 
and  stubby,  are  very  desirable  for  rubbing  paint 
on  to  metal  which  has  been  rusty  and  is  rough,  and 
for  similar  uses.  For  this  reason  brushes  should  be 
kept  clean  and  carefully  preserved.  The  best 
brushes  are  the  cheapest  in  the  end,  and  a  valuable 
brush  deserves  good  care.  Never  let  one  dry  with 
the  paint  in  it. 

\ 

Paint  Calculations 

Linseed  oil  is  usually  considered  to  weigh  7.76 
pounds  per  measured  gallon  (231  cu.  in.)  which 
corresponds  to  a  density  of  .931,  and  turpentine  is 
supposed  to  weigh  7.1  to  7.2  pounds,  or  to  have  a 
density  of  about  .86.  Commercial  (petroleum) 
benzine  weighs  about  6.2  pounds  per  gallon,  but  is 
variable.  A  gallon  of  water  at  ordinary  tempera- 
ture weighs  about  8.33  pounds  and  this  is  the  im- 
portant figure  to  remember.  If  we  multiply  this 
number,  8.33  by  6.6,  which  is  the  density  of  white- 
lead,  we  have  55  pounds,  which  is  the  amount  of 
dry  white-lead  required  to  make  a  gallon;  that  is, 
if  we  thoroughly  mix  55  pounds  of  dry  white-lead 
with  a  gallon  of  oil,  so  as  to  drive  all  the  air  out 
of  the  interstices  of  the  powder  and  replace  it  with 


Volume  Proportion 


77 


oil,  we  shall  have  exactly  two  gallons  of  a  mixture 
which  would  be  in  fluidity  intermediate  between  paste 
white-lead  and  a  paint;  but  if  we  mix  this  55  pounds 
of  dry  white-lead  v/ith  3  gallons  of  oil,  we  shall 
have  4  gallons  of  white-lead  paint.  In  the  same 
way  we  may  find  out  the  weight  of  any  pigment  re- 
quireci  to  make  up  the  volume  of  a  gallon  (when 
wetted  with  oil  or  other  vehicle),  by  multiplying 
8.33  pounds  by  the  figures  indicating  the  density 
of  the  pigment  in  question.  Thus,  the  density  of 
lampblack  is  1.82  and  if  we  multiply  8.33  pounds  by 
1.82  we  have  15  pounds,  which  amount  of  lamp- 
black mixed  with  7  gallons  of  oil  makes  8  gallons 
of  black  paint;  the  density  of  white  zinc  is  5.55  and 
multiplying  8.33  by  this  we  have  46  pounds  for  the 
weight  of  a  gallon  of  dry  white  zinc,  which  if  mixed 
with  6  gallons  of  oil  makes  7  gallons  of  white  zinc 
paint. 


Volume  Proportion 

It  will  be  noticed  that  to  enough  pigment  to  make 
a  gallon  we  add  in  the  case  of  white-lead  3  gallons 
of  oil,  with  lampblack  7  gallons,  and  with  white 
zinc  6  gallons.  There  is  no  rule  about  this;  the 
amount  of  oil  each  pigment  takes  is  found  out  ex- 
perimentally; but  white-lead  (or  perhaps  barytes) 
takes  the  least  and  lampblack  the  most  of  all  pig- 
ments.   The  volume  of  oil  is,  however,  much  more 


78 


Red-Lead  and  How  to  Use  it  in  Paint 


simply  related  to  the  volume  of  pigments  than  to 
their  weights.  In  general,  the  pigment  constitutes 
from  one-fourth  to  one-sixth  or  one-seventh  the 
volume  of  the  paint. 

A  practical  problem  of  this  sort  arises  in  a  case 
like  this:  red-lead  and  oil  make  a  paint  much  used 
in  painting  iron  and  steel;  the  red-lead  and  oil  are 
mixed  in  such  proportions  as  the  user  desires,  ac- 
cording to  the  character  of  the  work.  Thus,  33 
pounds  pigment  to  a  gallon  of  oil  is  used  for  under- 
water work;  28  pounds  pigment  to  a  gallon  for  other 
marine  work;  25  pounds  or  more  for  bridges,  and 
so  on.  To  find  the  cost  of  the  paint  in  each  case 
it  is  necessary  to  know  not  only  the  cost  of  materials, 
but  also  the  volume  of  paint  produced.  We  find 
by  computation  that  72  pounds  of  red-lead  make  a 
gallon;  then  33  pounds  equals  .46  gallon;  28  pounds 
equals  .38  gallon;  25  pounds  equals  .35  gallon  and 
so  on,  and  so  these  mixtures  will  amount  to  1.46 
gallons,  1.39  gallons,  1.35  gallons,  and  so  on. 
Multiplying  the  number  of  pounds  of  dry  pigment 
by  the  price  per  pound  and  adding  the  cost  of  a 
gallon  of  oil  gives  us  the  cost  of  materials  of  each 
of  these  various  amounts,  from  which  the  gallon 
prices  may  be  computed;  and  in  no  other  way  can 
it  be  done. 

Here  is  another  case :  Suppose  the  analysis  of  a 
paint  shows  80  per  cent  white-lead  and  20  per  cent 
asbestine,  by  weight,  in  the  pigment,  and  that  the 
consistency  of  the  paint  is  such  that  it  corresponds 
to  a  white-lead  paint  mixed  up  in  the  proportions 


V olume  Proportions 


79 


8o         Red-Lead  and  How  to  Use  it  in  Paint 

of  one  volume  of  dry  white-lead  to  three  volumes 
of  oil,  which  is  common.  We  know  that  92  pounds 
dry  white-lead  requires  8  pounds  oil  to  make  a 
paste;  and  we  also  know  that  a  given  volume  of 
asbestine  paste  contains  twice  as  much  oil  as  the 
same  volume  of  white-lead  paste.  It  takes,  we  find, 
55  pounds  dry  white-lead  to  make  a  gallon,  and  one- 
quarter  of  this,  14.25  pounds,  mixed  with  three- 
fourths  of  a  gallon  (5.81  pounds)  of  linseed  oil 
makes  a  gallon  of  paint.  If  92  pounds  white-lead 
take  8  pounds  oil  for  a  paste,  14.25  pounds  will 
take  1.24  pounds  (.16  gallon)  oil  to  make  a  paste 
and  the  rest  of  the  5.81  pounds  or  4.55  pounds  (.59 
gallon)  is  used  for  thinning  the  paste,  the  volume 
of  which  is  .41  gallon.  Practically,  we  are  taking 
one  and  a  half  volumes  of  oil  to  one  volume  of 
paste,  and  we  may  assume  (though  it  is  not  strictly 
accurate)  that  this  rule  will  apply  to  all  pastes  of 
similar  consistency. 


A  Sample  Problem 

We  find  by  computation  that  23  pounds  dry  as- 
bestine make  a  gallon;  and  to  find  the  composition 
of  a  gallon  of  asbestine  paint  we  may  proceed  as 
follows:  If  92  pounds  white-lead  and  8  pounds  oil 
make  a  paste,  an  amount  of  asbestine  correspond- 
ing to  84  pounds  of  white-lead  requires  16  pounds  of 
oil  (2.06  gallons).    Eighty-four  pounds  white-lead 


A  Sample  Problem 


8i 


equals  1.53  gallons  and  1.53  gallons  asbestine  equals 
35.2  pounds,  making  a  total  of  3.636  gallons.  This 
is  asbestine  paste;  to  make  this  into  paint  we  add 
(3-63X1^)  equals  5.45  gallons  oil,  making  9,1 
gallons  paint,  composed  of  35.2  pounds  asbestine, 
and  2.06+5.45  equals  7.51  gallons  oil;  and  i  gallon 
contains  .83  gallon  oil  and  3.86  pounds  asbestine. 
If  white-lead  costs  14  cents  and  asbestine  i  cents 
per  pound,  and  oil  $1  per  gallon  (which  are  usual 
prices)  the  white-lead  paint  will  cost  $2.75  per 
gallon  and  the  asbestine  paint  89  cents  per  gallon. 

Going  back  to  our  original  analyzed  paint,  it  con- 
tains 80  pounds  of  dry  white-lead  to  20  pounds  of 
asbestine.  If  i  gallon  of  white-lead  paint  contains 
14!/^  pounds  dry  white-lead,  80  pounds  will  make 
5.61  gallons,  and  20  pounds  asbestine  will  make 
5.44  gallons  or  11.05  gallons  altogether;  or  a  gallon 
contains  51  per  cent  of  white-lead  paint  and  49  per 
cent  of  asbestine  paint,  instead  of  80  and  20  as 
might  at  first  sight  be  thought,  and  the  cost  will  be 
$1.83  per  gallon,  instead  of  $2.63. 

We  are  liable  to  deceive  ourselves  as  to  the  value 
of  such  mixtures  unless  we  bear  these  principles  in 
mind. 

Similar  methods  may  be  used  for  paints  containing 
three  or  more  pigments. 

Calculations  of  paint  materials  are  based  primarily 
on  weight.  The  liquids  used  are  lighter  than  water; 
some  of  them  considerably  so;  the  pigments  are  all 
heavier  and  differ  much.  The  following  table  gives 
the  specific  gravity  of  the  more  important  ones;  and 


82 


Red-Lead  and  How  to  Use  it  in  Paint 


the  use  of  second  column  of  figures  is  explained  in 
the  preceding  text. 


SPECIFIC  GRAVITY 
Weight  Required  to  Make  a  Gallon 


Litharge  

Red-lead  

Orange  mineral  (orange  lead) . 

White-lead  

Basic  lead  sulphate  

Chrome  yellow  (medium)  

Zinc  oxide  (white  zinc)  

Basic  lead  chromate  

English  (mercury)  vermilion .  . 

Bright  red  oxide  of  iron  

Indian  red  oxide  of  iron  

Brown  oxide  of  iron  (Prince's) 

Ultramarine  

Prussian  blue  

Chrome  green,  blue  tone  

Chrome  green,  yellow  tone .... 

Lithopone  

Ocher  

Barytes  

Blanc  fixe  

Gypsum  (terra  alba)  

Asbestine  (magnesium  silicate) 
China  clay  (aluminum  silicate) 

Whiting   

Silica  

Natural  graphite  

Acheson's  graphite  

Lampblack  

Carbon-black  

Keystone  filler  (ground  slate) . 


Specific 
Gra^dty. 


9-3 
8.4  to  8.8 
8.6  to  8.7 

6.6 

6.4 

5-8 


5-55 
6.8 
8.2 
5.26 
5- 
3- 
2 . 
I . 
4- 


.26 
.  2 
•4 
•95 
•44 
4.0 

4-25 
2.94 
^.23  to  4.46 
4-25 

2-3 

2-75 
2.6  to  2.7 
2.6s 
2.65 

,6 
2 

85 
85 
66 


To  this  table  the  following  data  may  be  added: 
The  weight  of  one  gallon  of  paste  with 


A  Sample  Problem  83 

Red-lead   47.  pounds 

White-lead   35.6 

White  zinc   25  .  " 

Chrome  yellow  (medium)   30. 

Chrome  green   24. 

Venetian  red   19.  " 

French  ocher   13.6  " 

Prussian  blue   10.  " 

Lampblack   9.25  " 

A  gallon  of  most  paint  pastes  takes  about  i\/g 
gallons  of  oil  to  make  a  paint.     One  thousand 


pounds  of  white  zinc  paste  plus  878  gallons  raw 
oil  and  3  gallons  drier  makes  130  gallons  paint. 
White  zinc  paste  therefore  takes  much  more 
oil  than  most  paste;  and  in  fact  these  figures  are 
for  rather  stiff  pastes,  and  there  is  no  close  uni- 
formity in  the  amount  of  oil  they  take;  moreover, 
diffrent  painters  use  paints  of  different  degrees  of 
viscosity;  so  that  these  statements  as  to  pastes  are 
suggestions  rather  than  formulas.  As  such  the  writer 
finds  them  useful  memoranda. 

The  chrome  yellows  vary;  orange  chrome  has 
more  lead  in  it,  which  makes  it  heavier  than  medium 
chrome  yellow,  and  lemon  chrome  has  sulphate  of 
lead  in  it  (to  make  it  paler),  which  also  makes  it 
heavier.  The  density  of  red-lead  is  variable;  in 
general  the  higher  the  percentage  of  PbaO^  the 
lower  is  the  density;  but  this  is  also  influenced  by 
the  temperature  of  making  it  and  the  material  from 
which  it  is  made;  in  general,  crystals  are  heavier 
than  amorphous  bodies.  The  density  of  litharge 
varies  from  9.25  to  9.52;  some  of  it  is  crystallized 
from  a  fused  condition.  Orange  mineral  is  red-lead 
made  by  roasting  white-lead,  and  while  some  of  it 


84         Red-Lead  and  How  to  Use  it  in  Paint 

contains  considerable  PbO  and  is  correspondingly 
heavy,  some  of  it  has  as  little  as  .25  per  cent  PbO 
and  may  have  a  density  of  only  8.35. 


Thoroughness 


The  following  specifications  are  offered  for  gen- 
eral new  work.  In  an  appendix  will  be  found  a 
concise  set  of  specifications  for  miscellaneous  use; 
for  while  this  book  is  primarily  intended  to  give  in- 
formation rather  than  advice,  it  is  impossible  to 
resist  the  temptation  to  mix  the  two.  No  doubt 
most  people  will  think  the  ideas  thus  set  forth  as 
to  painting  are  extreme  in  the  matter  of  attention 
to  detail,  and  in  expense;  I  hope  so,  for  I  would 
not  willingly  contribute  anything  to  the  subject  which 
should  not  urge  an  improvement  in  current  practise, 
while  on  the  other  hand  there  is  nothing  prescribed 
which  I  have  not  seen  done,  in  one  form  or  another, 
many  times.  It  is  now  about  a  quarter  of  a  century 
since  I  published  my  first  general  specifications  for 
structural  painting,  and  it  is  good  to  be  able  to  say 
that  such  practise  is  now  far  more  common,  and  the 
average  of  such  work  is  considerably  higher,  than 
It  was  then;  it  would  be  foolish  to  think  that  this 
is  due  in  any  great  measure  to  the  influence  of  any 
one  man,  but  every  intelligent  discussion  of  it  helps 
to  create  and  sustain  its  interest  among  structural 
engineers  in  general,  the  only  source  from  which 
we  may  look  for  improvement.    By  a  steadily  in- 


specifications 


85 


creasing  number  of  Interested  experts  these  methods 
are  ceasing  to  be  regarded  as  academic;  and  while 
methods  are,  within  certain  limits,  more  important 
than  material,  it  is  time  to  insist  on  more  study  of 
the  latter.  During  the  last  fifteen  years  most  of 
the  author's  writings  have  been  on  the  subject  of 
materials  for  paint  and  varnish;  if  methods  of  ap- 
plication can  be  standardized,  excellence  and 
economy  in  results  depend  on  using  the  right  mate- 
rial in  its  own  proper  place.  For  more  than  a 
hundred  years  red-lead  has  occupied  an  important 
place  in  public  estimation;  now  more  than  ever,  in 
protection  of  structural  metal,  it  easily  heads  the  list. 

Specifications 

Shop  painting:  The  metal  shall  be  cleaned  so  as 
to  be  free  from  dirt,  rust  and  loose  scale;  this  shall 
be  done,  if  necessary,  by  thorough  scraping  and  wire- 
brushing;  grease  shall  be  removed  by  a  cloth  wet 
with  benzine.  Surfaces  to  be  riveted  shall  receive 
a  full  coat  of  heavy  red-lead  paint.  The  metal  shall 
be  painted  with  a  full  smooth  coat  of  paint  made 
as  follows:  To  100  pounds  of  paste  red-lead  shall 
be  added  2^  gallons  of  linseed  oil,  making  4.6  gal- 
lons of  paint;  or,  if  dry  red-lead  is  used,  to  each 
gallon  of  oil  28  pounds  of  dry  red-lead  shall  be 
added,  making  1.4  gallons  of  paint.  To  each  gallon 
of  this  may  be  added  at  the  discretion  of  either  the 
master-painter  or  the  inspector  not  more  than  one- 


86         Red-Lead  and  How  to  Use  it  in  Paint 

third  of  a  pint  of  drier;  also,  if  thought  best  one-third 
of  a  pint  of  mineral  turpentine. 

Striping  Coat 

Second  coat:  After  erection,  dirt  and  grease  shall 
be  removed;  all  places  not  well  covered  with  paint 
shall  be  repainted,  all  rivet  and  bolt  heads  shall  be 
painted,  all  edges  shall  receive  a  striping  coat  ex- 
tending an  inch  from  the  edge;  and  when  this  paint 
is  dry  one  full  coat  of  paint  shall  be  applied  over 
the  whole  surface.  This  paint  shall  be  made  as 
follows:  To  ICQ  pounds  of  paste  red-lead  shall 
be  added  ^  pound  of  paste  lampblack  and  2  5/^  gal- 
lons of  linseed  oil,  making  4V5  gallons  of  paint;  or, 
to  each  gallon  of  oil  27  pounds  of  dry  red-lead  and 
2^  ounces  of  paste  lampblack  shall  be  added,  mak- 
ing 1.45  gallons  of  paint;  to  this  drier  and  turpentine 
may  be  added  as  for  the  shop  coat. 

Third  coat:  This  shall  be  of  paint  made  as  fol- 
lows: To  ICQ  pounds  of  paste  red-lead  shall  be 
added  6  pounds  paste  lampblack  and  3.25  gallons 
of  linseed  oil,  making  5.6  gallons  of  paint;  or,  to 
each  gallon  of  linseed  oil  add  23  pounds  of  dry  red- 
lead  and  1.5  pounds  of  paste  lampblack,  making 
1.5  gallons  of  paint;  and  drier  and  turpentine  as 
before.  (This  last  is  about  the  same  as  adding  26 
pounds  dry  red-lead  to  a  gallon  of  oil,  and  then 
adding  gallon  of  lampblack  paint,  with  drier  and 
turpentine.)     For  use  in  a  dry  climate  the  propor- 


Drier  and  Turpe7itine 


87 


tlon  of  oil  in  the  last  coat  may  be  increased  one-tenth 
or  a  little  more. 

It  is  to  be  remembered  that  because  paste  lamp- 
black Is  four-fifths  oil  it  tends  to  make  the  film  softer 
and  more  elastic.  It  is  desirable  to  have  outer  coats 
more  so  than  those  beneath,  so  that  weather  ex- 
posure will  finally  bring  them  all  to  about  the  same 
hardness.    But  not  so  for  underwater  paints. 

All  outdoor  painting  shall  be  done  in  fair  weather, 
temperature  not  below  50°  Fahrenheit. 


Quality  of  Materials 

The  paste  red-lead  shall  contain  from  6  to  7^ 
per  cent  of  linseed  oil;  shall  contain  only  pure  linseed 
oil  and  red-lead  analyzing  97  per  cent  (or  more) 
Pb304;  dry  red-lead  shall  analyze  94  per  cent  (or 
more)  PbsO^;  the  oil  shall  be  pure  linseed  oil  agree- 
ing with  the  specifications  of  the  American  Society 
for  Testing  Materials,  shall  be  aged  at  least  one 
month,  and  a  sample  after  standing  twenty-four 
hours  in  a  graduated  cylinder  at  a  temperature  of 
not  less  than  70°  Fahrenheit  shall  not  show  more 
than  1 per  cent  of  sediment,  by  volume. 

Drier  and  Turpentine 

The  drier  shall  be  a  light-colored  drier,  shall  be 
guaranteed  free  from  rosin,  and  to  contain  both  lead 


88 


Red'Lead  and  How  to  Use  it  in  Paint 


and  manganese,  the  proportion  of  lead  not  less  than 
three  times  that  of  manganese.  Raw  linseed  oil  to 
which  lo  per  cent  of  this  drier  has  been  added  shall 
make  a  film  on  glass  which  will  be  dry  to  the  touch 
after  12  hours'  drying  at  60°  Fahrenheit,  indoors, 
in  moderately  dry  weather. 

A  rosin-free  drier  may  always  be  obtained  on 
orders  of  considerable  size,  and  is  safer  and  prob- 
ably better  than  the  more  common  driers  which 
contain  rosin;  when  oil  is  high  it  is  a  little  more 
costly.  There  is  some  doubt  as  to  whether  a  small 
amount  of  combined  rosin  is  harmful,  and  probably 
most  of  the  rosin-containing  driers  sent  out  from 
factories  of  first-class  reputation  are  satisfactory. 
A  large  amount  of  rosin  is  objectionable,  and  it  is 
difficult  to  tell  by  analysis  how  much  is  present  if 
any  is  permitted.  Too  much  drier  lessens  durability. 
Sometimes  formulas  are  seen  calling  for  large  pro- 
portions— 10  to  25  per  cent — of  drier,  or  ^'japan 
drier";  in  these  paints  the  drier  is  not  put  in  for 
its  usual  purpose,  but  to  make  the  paint  take  a  quick, 
almost  instantaneous  initial  set,  so  that  it  may  not 
''run.''  This  is  done  for  several  reasons;  and  espe- 
cially with  coarse  pigments;  but  always  when  you  see 
a  very  large  proportion  of  japan  drier  used,  it  is 
for  some  special  purpose,  and  not  as  an  ordinary 
catalyzer.    Drier  is  a  thinner,  the  same  as  turpentine. 

In  metal  painting  turpentine  may  almost  always 
be  replaced  by  ''mineral  turpentine,"  as  has  been 
explained  elsewhere. 


Notes  on  the  Foregoing  Specifications  89 


Notes  on  the  Foregoing  Specifications 

The  United  States  Navy  specification  for  paste 
red-leaci,  before  the  war  interfered  with  the  supply, 
was  essentially  as  follows: 

Guaranty 

The  paste  shall  be  of  high-grade  quality,  free 
from  all  adulterants,  and  the  pigment  shall  show 
on  analysis  not  less  than  97  per  cent  of  true  red-lead 
(Pb304)  ;  shall  be  equal  to  the  standard  sample  in 
freedom  from  vitrified  particles  and  in  other  re- 
spects; shall  be  guaranteed  against  hardening  in  the 
original  container  if  kept  sealed  at  ordinary  tem- 
perature for  a  period  of  three  months. 

A  somewhat  simpler  specification  would  be:  The 
paste  shall  contain  only  red-lead  and  6  to  7  per 
cent  of  linseed  oil  and  shall  be  guaranteed  for  three 
months  against  hardening  if  kept  sealed  in  the 
original  package  at  ordinary  temperature. 

If  the  pigment  and  oil  are  pure,  the  former  will 
have  to  be  97  per  cent  Pb304  or  it  will  harden;  if 
it  is  97  per  cent  it  will  have  to  be  fine,  and  right 
every  way. 

Oil 

The  specification  for  linseed  oil  is  the  best  known, 
and  should  be  satisfactory.  That  for  drier  is  not 
so  definite,  but  will  be  easily  understood,  and  should 


90 


Red-Lead  and  How  to  Use  it  in  Paint 


be  sufficient.  Painters  know  the  difference  In  color 
between  pale  and  dark  driers.  If  it  Is  preferred  to 
use  boiled  oil,  It  is  recommended  for  ordinary  work 
to  use  one-third  to  one-half  boiled  oil,  which  shouki 
agree  with  A.  S.  T.  M.  specification,  and  the  rest 
raw  oil,  and  no  drier,  or  very  little.  The  attention 
of  the  inspector  should  be  drawn  to  the  fact  that 
when  linseed  oil  is  scarce  and  high  In  price  It  Is  often 
adulterated;  If  bought  direct  from  the  manufacturer 
it  Is  reasonably  sure  to  be  pure,  but  there  Is  never 
any  certainty  about  Its  freedom  from  ^^foots";  if 
bought  two  cents  a  gallon  below  open  market  quota- 
tions, it  must  be  regarded  with  suspicion,  which  at 
a  less  price  Is  greatly  Increased;  soon  a  point  is 
reached  where  nobody  Is  to  be  believed  except  a 
good  testing  laboratory. 

Dry  pigments  should  never  be  added  to  the  full 
amount  of  oil,  but  mixed  with  a  little  oil  to  a  per- 
fectly wetted  paste,  and  the  rest  of  the  oil  added, 
a  little  at  a  time,  and  well  stirred  In.  All  pastes 
are  better  if  passed  through  a  mill. 

It  is  the  practise  of  all  good  painters  to  strain 
all  liquid  paints,  which  have  been  standing  more 
than  a  day  or  so,  through  cheese-cloth,  or  at  least 
through  a  sieve. 

Heavier  paint,  that  Is,  containing  more  red-lead, 
may  be  used  throughout  and  would  doubtless  be 
better. 

It  is  of  course  understood  that  if  the  engineer  feels 
at  liberty  to  specify  sand-blasting  or  pickling,  he  will 
do  so. 


Notes  071  the  Foregoing  Specifications 


91 


Area  Covered 

The  steel  viaduct  of  the  Nickel  Plate  Railroad 
in  South  Chicago  is  of  very  heavy  plate  girders,  and 
a  gallon  of  heavy  red-lead  paint  covered  twenty  tons 
with  one  coat;  this  was  the  average  of  the  whole 
bridge.  The  same  road  has  bridges  which,  because 
of  lighter  structure,  take  seven  times  as  much  paint 
per  ton.  If  on  the  same  road  the  paint  per  ton 
varies  600  per  cent,  it  is  obvious  that  tonnage  is 
not  a  good  basis  for  estimating  the  amount  of  paint 
required.    We  paint  surface  and  not  tonnage. 

As  to  the  area  which  a  gallon  of  paint  will  cover 
much  might  be  said,  because  widely  different  results 
are  obtained  by  different  painters.  Contractors' 
painters  are  likely  to  spread  it  over  as  much  surface 
as  they  can;  and  the  regular  painting  team  of  a 
railroad  may  be  trained  to  put  on  as  full  a  coat  as 
they  can.  Also  a  smooth  surface,  like  a  large  water 
tank,  or  a  gas-holder,  takes  a  uniform  coat  which 
is  therefore  spread  over  more  area  than  the  irregu- 
larities of  a  latticed  girder.  Further,  the  surface 
of  bridge-work  is  not  easily  computed. 

The  following  figures  are  for  paint  made  from 
paste  red-lead: 

The  Long  Island  Railroad  engineers  have  an  ex- 
cellent painter  who  believes  in  full  coats;  they  re- 
port a  gallon  of  red-lead  paint  covers  650  square 
feet.  The  United  Gas  Company  of  Philadelphia 
use  a  heavy  paint  and  on  gas-holders  covers  900 


Notes  on  the  Foregoing  Specifications 


93 


square  feet.  The  contractors  for  an  important 
Pennsylvania  Railroad  bridge  covered  900  square 
feet.  The  Maryland  Steel  Company  report  840 
square  feet  on  a  new  ship's  hull,  using  a  heavy  paint; 
they  had  never  covered  more  than  600  square  feet 
with  a  similar  paint  made  from  dry  red-lead.  The 
engineers  of  the  Massachusetts  water  commission 
report  700  square  feet  on  large  tanks,  using  paint 
made  from  100  pounds  paste  red-lead  to  2  gallons 
oil  (equivalent  33  pounds  dry  red-lead  to  i  gallon 
oil).  The  master-painter  of  the  Fore  River  Ship- 
building Company,  where  more  than  200  tons  of 
paste  red-lead  have  been  used,  reports  that  it  covers 
a  third  more  surface  than  similar  paint  made  from 
dry  red-lead;  as  this  paint  is  Navy  Department 
formula  and  the  Navy  handbook  estimates  504 
square  feet  for  a  gallon  made  from  dry  red-lead, 
this  probably  corresponds  to  700  square  feet. 
The  present  opinion  of  the  writer,  based  on  such 
figures  as  seem  reliable,  is  that  such  a  paint  as  is 
advised  in  these  specifications  may  be  expected  to 
cover  at  least  700  square  feet  per  gallon,  with  large 
allowance  both  ways  for  differences  in  conditions. 
White-lead  paint,  except  in  priming  coats  on  wood, 
often  covers  more  than  this.  Red-  and  white-lead 
have  more  affinity  for  oil  than  other  paints,  and  if 
finely  ground  cover  more  surface  than  most — per- 
haps all — other  pigments.  Any  good  paint  on  a 
smooth  hard  surface  can  be  brushed  out  to  cover 
1500  square  feet,  but  3uch  a  film  is  too  thin  to  be 
of  service, 


94 


Red-Lead  and  How  to  Use  it  in  Paint 


Spreading  Capacity 

The  quantity  of  paint  required  to  coat  a  given 
number  of  tons  of  structural  steel  in  a  bridge, 
building,  or  similar  structure  is  determined  by  the 
area  of  the  surface  to  be  covered  and  the  spreading 
capacity  of  the  paint  to  be  used.  The  spreading 
capacity  varies  greatly  with  different  paints,  but  in 
the  case  of  red-lead  it  varies  with  the  fineness  of  the 
pigment,  its  freedom  from  sandy  lead,  its  specific 
gravity,  the  consistency  of  the  paint  after  the  vehicle 
and  pigment  are  thoroughly  mixed,  the  amount  of 
thinner  used,  and  the  amount  of  brushing  out  given 
to  the  paint  on  the  surface  to  which  it  is  applied. 
The  condition  of  the  surface  has  an  even  greater 
influence  on  the  amount  of  paint  required  than  any 
of  the  characteristics  of  the  paint  itself  mentioned 
above.  On  a  smooth  rolled  plate  a  paint  may  be 
spread  over  fully  50  per  cent  more  area  than  on  a 
rough,  porous,  or  rusty  surface. 

The  area  of  the  surface  to  be  covered  varies 
greatly  with  the  character  of  the  construction,  this 
variation  being  independent  of  the  tonnage.  A  plate 
girder  bridge  whose  average  cross-section  is  i  inch 
thick  will  have  an  exposed  area  to  be  painted  of 
a  little  more  than  120  square  feet  per  ton  of  steel, 
while  a  heavier  girder,  averaging  ly^  inches  in  thick- 
ness, would  have  only  about  90  square  feet  of  sur- 
face per  ton.  A  moderately  heavy  building  frame- 
work whose  columns,  girders,  and  beams  are  about 


Notes  on  the  Foregoing  Specifications 


95 


Yz  inch  thick,  will  present  a  painting  area  of  about 
250  square  feet  per  ton  of  steel,  while  that  required 
for  a  lighter  structure  whose  members  have  an 
average  thickness  of  about  ^4  i^^^h  will  be  about 
500  square  feet  per  ton.  A  very  light  lattice  struc- 
ture whose  angles  and  straps  will  average  Vs  to  Vie 
inch  in  thickness  will  have  a  superficial  area  of  from 
770  to  1000  square  feet  per  ton. 

The  surface  area  of  structural  steel  may,  there- 
fore, be  said  to  vary  between  100  and  1000  square 
feet  per  ton,  and  it  is  obviously  very  difficult  to 
formulate  any  fixed  and  simple  rule  for  estimating 
accurately  the  quantity  of  red-lead  paint  required 
for  painting  such  material. 

General  rules  can,  however,  be  laid  down,  which 
when  used  in  conjunction  with  data  on  the  general 
character  of  the  structure  to  be  painted  will  give  a 
reasonably  close  estimate  of  the  amount  of  paint 
required. 

It  may  safely  be  stated  that  a  pure  red-lead  paint, 
mixed  in  the  proportion  of  28  pounds  of  dry  red- 
lead  to  I  gallon  of  pure  linseed  oil,  without  turpen- 
tine or  other  thinner,  when  applied  to  average  new 
structural  steel  surfaces  will  cover  from  600  to  700 
square  feet  per  gallon  for  the  first  coat,  from  700 
to  800  square  feet  for  the  second  coat,  and  from 
800  to  900  square  feet  for  the  third  coat.  By  com- 
bining these  fiugures  we  find  that  for  two-coat  work 
— that  is,  for  the  first  two  coats,  the  shop  coat  and 
the  first  field  coat — i  gallon  of  paint  will  cover  from 
300  to  400  square  feet,  and  for  three-coat  work  i 


Red-Lead  and  How  to  Use  it  in  Paint 


gallon  will  be  required  for  every  225  to  275  square 
feet. 

It  is  impossible  to  make  anything  but  very 
general  statements  as  to  the  area  to  be  painted  on 
a  ton  of  steel,  varying  as  it  does  from  100  to  1000 
square  feet.  In  order  to  arrive  at  the  approximate 
average  thickness  of  the  metal  or  the  area  of  surface 
per  ton,  some  study  of  the  drawings  Is  necessary. 
To  assist  in  forming  an  approximate  estimate  of  the 
area  per  ton,  Tables  i,  2  and  3  have  been  prepared. 
Table  i  shows  the  superficial  area  per  ton  of  iron 
or  steel  plate  for  thicknesses  ranging  from  ^  to 
2  inches,  and  Tables  2  and  3  give  the  area  per  ton 
of  the  different  shapes  commonly  used  in  steel  con- 
struction. With  the  aid  of  these  tables  and  the  plans 
of  the  structure  to  be  painted  the  approximate  area 
per  ton  may  be  determined. 

As  an  example,  assume  a  heavy  plate  girder  bridge 
whose  members,  according  to  the  plans,  have  an 
average  thickness  of  ij4  inches.  By  referring  to 
Table  i  we  find  that  this  thickness  of  metal  has  an 
area  of  80  square  feet  per  ton.  Allowing  about  10 
per  cent  for  edges,  rivet  heads,  and  other  irregulari- 
ties, which  in  the  case  of  such  heavy  construction  is  a 
very  liberal  allowance,  we  have  an  area  of  88  square 
feet  per  ton.  With  such  conditions  a  first  or  primary 
coat  would  require  about  ^/^  gallon  per  ton.  For 
two  coats  ^  gallon  would  be  required,  and  ^  gal- 
lons for  three  coats. 

As  another  example,  assume  the  structure  to  be 
a  building  frame  with  columns,  girders,  and  beams. 


Notes  on  the  Foregoing  Specifications 


97 


TABLE  1 
Area  of  Surface  of  Plate  per  Ton 
Based  on  Iron  Weighing  480  lbs.  per  Cubic  Foot 


Thickness  of 

Area  in  Sq.  Ft. 

Inickness  01 

Area  in  Sq.  Ft. 

Metal,  Inches. 

pel    OllUiL    ±  Ull. 

IVACltll,  XllCIICb. 

per  Short  Fon. 

1 

8 

800 

I 

100 

3 

Ivi 

533 

i-i 

89 

1 

400 

li 

80 

5 

10 

320 

if 

73 

3 
8 

267 

li 

67 

1 

2 

200 

if 

62 

160 

li 

57 

3 
4 

133 

i| 

53 

7 

8 

114 

2 

50 

TABLE  2 

Area  of  Surface  of  I-Beams  and  Channels  per  Ton 
Standard  and  Special  I-Beams 


Section  No. 

Depth, 
Inches. 

Minimum 

Sections, 

Maximum 

Sections, 

in  Cambria 

Pounds 

Sq.  Ft. 

Pounds 

Sq  Ft. 

Book. 

per  Foot. 

per  Ton. 

per  Foot. 

per  Ton 

Standard 

B  5 

3 

5-5 

422 

7-5 

317.2 

B  9 

4 

7-5 

379 

10-5 

277.8 

B  13 

5 

9-75 

346.8 

14-75 

235-4 

B  17 

6 

12.25 

319.8 

17-25 

231.2 

B  21 

7 

15-0 

294.6 

20.0 

224.  2 

B  25 

8 

18.0 

275-3 

25-25 

199.8 

B  29 

9 

21.0 

261 .0 

35-0 

161 . 0 

B33 

10 

25.0 

244.0 

40.0 

^53-6 

B  41 

12 

31-5 

217.8 

50.0 

173-4 

B  53 

15 

42 .0 

193-5 

60.0 

137-4 

B65 

18 

55-0 

171 . 0 

70.0 

135-6 

B  73 

20 

65.0 

I57-0 

75-0 

136.8 

B  89 

24 

80.0 

150.2 

100. 0 

121 . 0 

Red-Lead  and  How  to  Use  it  in  Paint 

TABLE  2 — Continued 


Standard  and  Special  I -Beams 


Section  No. 

Depth, 

Minimum 

Sections, 

Maximum 

Sections, 

in  Cambria 

Inches. 

Pounds 

Sq.  Ft. 

Pounds 

Sq.  Ft. 

Book. 

per  Foot. 

per  Ton. 

per  Foot. 

per  Ton. 

Special 

B  105 

12 

40 

0 

181 

7 

55-0 

1343 

B  109 

15 

60 

0 

139 

0 

80.0 

105.8 

B  113 

15 

80 

0 

105 

8 

100.0 

85-9 

B  121 

20 

80.0 

132 

7 

100.0 

107 .0 

Standard  and  Special  Channels 

Standard 

c  S 

3 

4 

0 

447 

6 . 00 

303-0 

C  9 

4 

5 

25 

424 

7-25 

3130 

C  13 

5 

6 

5 

408 

11.50 

238.8 

C  17 

6 

8 

0 

366 

15-50 

206.9 

C  21 

7 

9 

75 

361 

6 

1975 

185-5 

C  25 

8 

II 

25 

350 

8 

21.25 

191. 7 

C  29 

9 

13 

25 

331 

0 

25.00 

180.4 

C  33 

10 

15 

0 

321 

3 

35  00 

143-4 

C  41 

12 

20 

5 

277 

2 

40. 00 

146. 1 

C  S3 

15 

33 

0 

209 

0 

55-0 

128.3 

Special 

C  91 

12 

21 

4 

254 

8 

33-9 

163.6 

C  95 

13 

32 

0 

207 

0 

55-0 

123.6 

Special  Shi 

Channels 

C  86 

6 

15 

2 

271 . 

0 

C  88 

6 

19 

0 

211 . 

2 

21 . 6 

1^8.4 

C  89 

7 

20 

9 

209. 

4 

8 

C  90 

9 

10 

21 

70 

246. 

2 

Notes  on  the  Foregoing  Specifications 


99 


TABLE  3 

Areas  or  Surface  of  Angles  and  Z-Bars  per  Ton 


Standard  Angles  with  Equal  and  Unequal  Legs 


Section  No. 

Uimen- 

Minimum 

bections, 

iVlcLXlIIlUlIl 

OCCLlOIlb, 

in  Cambria 

sions  J 

Pounds 

Sq.  Ft. 

Sq.  Ft. 

Book. 

lilLllCb. 

per  Foot. 

X  cr  -1.  (jii. 

pel  1  uuu. 

pel    ±  Ull. 

Standard 

0 

Equal  Legs 

A 

5 

3  V/  3 

4  /\  4 

0 

.60 

790.0 

0 .  09 

Uoy  .  0 

A 

7 

iXi 

0 

.80 

732.5 

I -50 

390.0 

A 

9 

I 

10 

644-5 

2.40 

295.2 

A 

II 

I2  XI2 

I 

30 

746.0 

3-90 

240 .  0 

A 

13 

t3  V 
I4  A  I4 

2 

20 

509.0 

5  •  10 

219.2 

A 

15 

2 

50 

516.0 

2 14  •  6 

A 

17 

z  2  /N  ^  2 

3 

10 

523  •  5 

5  .  50 

191  •  I 

A 

19 

3/\3 

4 

90 

390  .  5 

12  .  50 

155-4 

A 

21 

32  A32 

7 

20 

314-  2 

io .  30 

124.6 

A 

23 

/I  V  /I 

8 

20 

321  .  5 

120.4 

A 

27 

U  /\  u 

14 

90 

zUz  .  0 

3  7 . 40 

104. 7 

A 

35 

0  A  0 

26 

40 

199.  I 

56.90 

92.4 

Standard 

Unequal  Le 

A 

91 

2iX2 

2 

8 

519-0 

7.6 

191-3 

A 

93 

3X2i 

4 

5 

394-6 

10.4 

170.6. 

A 

95 

34X2i 

4 

9 

396.3 

13-4 

145 -o 

A 

97 

3^X3 

6 

6 

316.0 

16.8 

130. 1 

A 

99 

4X3 

7 

2 

303-8 

18.3 

II9-5 

A 

lOI 

5X3 

8 

2 

307-4 

21  .  2 

118. 9 

A 

103 

5X3* 

8. 

7 

317.2 

24.  2 

114. 0 

A 

105 

6X3i 

II . 

7 

262.8 

28.9 

102.8 

A 

107 

6X4 

12 . 

3 

261.8 

30.6 

104. 0 

lOO       Red-Lead  and  How  to  Use  it  in  Paint 

TABLE  3 — Continued 


Standard  and  Special  Z-Bars 


Section  No. 

Dimen- 

Minimum 

Sections, 

Maximum 

Sections, 

in  Cambria 

sions, 

Pounds 

Sq.  Ft. 

Pounds 

Sq.  Ft. 

Book. 

Inches. 

per  Foot. 

per  Ton. 

per  Foot. 

per  Ton. 

Standard 

Z 

5 

3 

0 

6 

7 

384 

0 

8 

4 

309 . 0 

Z 

9 

3 

9 

7 

259 

6 

II 

4 

231 . 2 

z 

13 

3 

0 

12 

5 

210 

8 

14 

2 

188.4 

z 

21 

4 

0 

8 

2 

377 

2 

12 

4 

256.0 

z 

25 

4 

0 

13 

8 

228 

8 

17 

9 

181. 0 

z 

29 

4 

0 

18 

9 

170 

4 

23 

0 

143.8 

z 

37 

5 

0 

II 

6 

304 

8 

16 

4 

217.2 

z 

41 

5 

0 

17 

9 

210 

0 

22 

6 

162.3 

z 

45 

5 

0 

23 

7 

154 

2 

28 

3 

132.3 

z 

53 

6 

0 

15 

6 

257 

2 

21 

0 

194.8 

z 

57 

6 

0 

22 

7 

179 

5 

28 

I 

147 -9 

z 

6i 

6 

0 

29 

3 

141 

2 

34 

6 

123.0 

special 

Z 

67 

7 

5 

16 

3 

264 

6 

z 

73 

8 

0 

22 

I 

202 

4 

If  the  columns  are  lo-inches  channels  of  minimum 
weight,  latticed  on  two  sides  with  Vie-inch  straps, 
such  a  column  would  have  an  area  per  ton  of  321.3 
square  feet  for  the  channels  and  320  square  feet 
for  the  straps,  or  the  combination  might  average 
320.7  square  feet  per  ton.  If  the  girders  are  18- 
Inch  maximum-weight  I-beams  they  would  have  an 
area  of  135.6  square  feet  per  ton,  while  if  the  beams 
are  8-inch  11.25-pound  channels,  they  would  have  a 
surface  of  350.8  square  feet  per  ton.    The  whole 


Notes  on  the  Foregoing  Specifications 


lOI 


combination  might  be  judged  to  average  300  square 
feet  per  ton  and  would  therefore  require  between 
V5  and  V2  gallon  of  paint  for  the  first  coat,  %  to 
1.  gallon  per  ton  for  the  first  two  coats,  and  i}^  to 
gallons  for  three  coats. 

In  estimating  the  cost  of  paint  materials  from  the 
data  which  have  been  given,  it  must  be  remembered 
that  all  figures  are  based  on  the  measured  gallon  of 
231  cubic  inches,  and  that  while  a  gallon  of  linseed 
oil  weighs  7.75  pounds,  the  trade  has  always  used 
a  trade  gallon  of  7^^  pounds  of  linseed  oil,  and  in 
buying  oil  in  barrels  this  is  what  is  bought;  about 
3  per  cent  more  is  needed  than  of  measured  gallons. 

This  is  what  the  writer  thinks  ought  to  be  used; 
but  experience  shows  that  less  paint,  that  is,  thinner 
coats  and  more  spreading  with  the  brush,  is  the 
average  practise;  and  that  60  to  70  per  cent  of  these 
amounts  of  paint  are  in  more  general  use. 

There  is  no  use  in  shutting  our  eyes  to  facts. 
There  is  the  compensating  consideration  that  paint 
must  be  well  brushed  out  to  cover  more  surface,  and 
this  is  as  important  as  anything  can  be. 

Since  the  advent  of  very  high  grade  (paste)  red- 
lead  the  writer  has  carried  on  systematic  inquiries 
as  to  painters'  practise  with  it;  and  while  the  follow- 
ing general  rule  must  be  taken  with  consideration  of 
the  foregoing  discussion,  it  is  certainly  a  convenient 
thing  to  have  a  middle  ground  from  which  to  look 
over  the  situation: 

On  medium  weight  bridges,  ^  gallon  per 

TON    FOR    FIRST    COAT;  GALLON    FOR  SECOND 


102 


Red-Lead  and  How  to  Use  it  m  Paint 


COAT;  GALLON  FOR  FINISHING  COAT;  OR  %  GAL- 
LON FOR  THREE  COATS.  HEAVIER  BRIDGES  LESS, 
AND    LIGHTER    MORE,    PER    TON.      Roofs    lOOO  tO 

I200  square  feet  per  gallon. 

As  a  Paint  for  Wood 

It  Is  generally  assumed  that  white-lead  is  the  best 
priming  coat  for  wood;  but  the  fact  is  that  there  is 
nothing  which  will  always  prove  satisfactory.  For 
many  years  red-lead  has  been  used  for  this  purpose 
in  England;  this  practise  has  been  introduced  into 
the  United  States  through  Canada,  and  has  been 
growing  in  favor  for  at  least  ten  or  twelve  years, 
although  it  cannot  be  said  to  have  become  very  ex- 
tensive. It  has  already  been  said  (p.  24)  that,  in 
general,  successive  coats  of  paint  should  be  progres- 
sively more  elastic;  and  to  make  a  hard  undercoat 
only  a  small  amount  of  oil  is  mixed  with  the  pigment. 
On  the  other  hand,  wood,  unlike  metal,  absorbs  oil; 
hence  it  is  necessary  to  use  considerable  oil  in  the 
priming  coat,  or  else  the  oil  will  all  go  into  the  wood 
and  leave  the  pigment  as  a  dry,  non-adhesive  coating, 
not  fit  to  bind  the  next  coat  to  the  wood.  But  if 
the  wood  surface  is  full  of  pitch  the  oil  is  not  readily 
absorbed;  this  gives  rise  to  the  practise  of  using 
with  the  oil  a  considerable  amount  of  turpentine, 
which  has  a  solvent  action  on  the  pitch,  and  makes 
the  absorption  more  uniform. 

For  some  unknown  reason,  red-lead  is  less  likely 
to  soften  and  blister  over  these  pitchy  spots  than 
white-lead.    The  writer  formerly  supposed  that  this 


I04        Red-Lead  and  How  to  Use  it  in  Paint 


might  possibly  be  due  to  chemical  action  between 
the  litharge  of  the  red-lead  and  the  resinous  matter; 
but  experience  shows  no  difference  in  behavior  be- 
tween red-leads  containing  85  to  98  per  cent  PbsOi, 
so  that  theory  has  been  given  up.  But  it  seems  to  be 
true  that  red-lead  paint  sticks  better  than  white  to 
such  surfaces,  and  that  is  the  practical  thing  to  know. 
And  as  red-lead  paint  is  harder  than  white-lead,  and 
no  less  tough,  it  naturally  makes  a  good  priming 
coat  for  any  kind  of  wood.  Its  color  is  against  it, 
if  the  finish  is  to  be  white;  two  coats  of  white-lead 
over  it  will  still  show  a  little  red;  but  two  coats  of 
light  gray  or  any  corresponding  tint  will  not  be  con- 
siderably, if  at  all,  affected;  for  the  opacity  of  any 
tinted  paint  is  much  greater  than  that  of  white. 
Half  white-  and  half  red-lead  for  a  priming  coat 
may  be  used,  even  if  the  finish  is  to  be  white. 

A  good  priming  coat  for  yellow  pine  and  the  like 
is  as  follows : 

100  pounds  paste  red-lead, 
gallons  raw  linseed  oil. 
gallons  turpentine, 
gallon  drier. 

6  gallons  of  paint. 
Or  for  white  pine,  white  wood,  or  poplar: 
100  pounds  paste  red-lead. 
4}^  gallons  raw  linseed  oil. 
y2  gallon  turpentine, 
gallon  drier. 

7!/^  gallons  of  paint. 


Notes  071  the  Foregoing  Specifications  105 


A  skillful  English  painter,  of  long  experience,  re- 
cently wrote  to  the  author,  urging  more  extended 
descriptions  of  the  use  of  red-lead  in  house-painting, 
especially  for  interiors,  as  ^'it  gives  a  splendid  foun- 
dation upon  which  to  build  the  succeeding  coats  of 
paint,  without  the  necessity  of  shellacking.  The  red 
color  is  of  no  consequence,  as  three  coats  are  usually 
given  on  interior  surfaces  anyway." 

There  is  no  doubt  that  architects  should  be  more 
familiar  with  its  use  on  metal  roofs,  and  especially 
on  valleys,  gutters  and  down-spouts;  and  on  metal 
railings,  which  are  particularly  troublesome  to  clean 
if  they  ever  become  rusty,  because  of  their  irregular 
and  intricate  forms.  The  architect  should  also  be 
particular  to  advise  frequently  repainting  of  valleys 
in  roofs,  and  it  is  in  these  that  leaks  most  frequently 
start,  causing  much  damage.  The  thorough  painting 
of  all  exposed  metal  work  about  buildings  is  of  im- 
portance, because  its  renewal  is  so  expensive,  not 
merely  because  of  the  cost  of  material  but  still  more 
from  the  inconvenience  and  excessive  labor  cost  of 
replacement. 

The  appreciation  of  these  things  has  led  the 
author  to  include,  among  the  specifications  in  the  ap- 
pendix, some  for  the  architect's  guidance. 


APPENDIX  I 


Analytical  Method 

At  the  191 7  meeting  of  the  American  Society  for 
Testing  Materials,  a  method  for  testing  red-lead 
was  adopted  as  standard.  This  is  herewith  given. 
The  same  method  has  long  been  in  use  in  the  labora- 
tory of  the  National  Lead  Company,  and  their  state- 
ment of  it  is  added,  with  the  thought  that  by  com- 
parison any  step  which  may  seem  obscure  to  the 
inexperienced  analyst  may  be  made  more  clear. 

It  should  be  observed  that  the  analysis  of  paste 
red-lead  presents  a  special  difficulty,  because  oil  ad- 
heres to  it  with  great  persistence.  Petrolic  ether 
will  not  remove  it,  nor  will  ethyl  ether  do  so  com- 
pletely. After  washing  with  the  latter  the  pigment 
should  be  washed  in  a  Soxhlet  apparatus,  with  a 
mixture  of  one  part  acetone  and  three  or  four  of 
benzole  or  chloroform;  even  then  a  trace  of  oil 
probably  remains,  for  paste  made  from  98  per  cent 
PbsOi  gives  on  analysis  only  96  to  97  per  cent,  and 
allowance  should  be  made  for  this. 


107 


io8       Red-Lead  and  How  to  Use  it  in  Paint 
METHOD  FOR  ANALYSIS  OF  RED-LEAD^ 

OF 

AMERICAN  SOCIETY  FOR  TESTING 
MATERIALS 

Approximate  formula  may  be  considered  as 
PbsO,  (probably  PbO,2PbO). 

Apparent  gravity  and  true  specific  gravity  de- 
termined as  per  methods  under  white  pigments. 

Fineness. — Wash  lo  g.  with  water  through  No. 
21  silk  bolting  cloth;  dry  and  weigh  residue. 

Moisture. — Dry  2  g.  of  the  sample  for  2  hours 
at  105°  C.  The  loss  in  weight  is  considered  as 
moisture. 

Organic  Color. — Boil  2  g.  of  the  sample  with 
25  cc.  of  95  per  cent  ethyl  alcohol;  let  settle,  decant 
off  the  supernatant  liquid;  boil  residue  with  water, 
decant  as  before  and  boil  residue  with  very  dilute 
NH4OH.  If  either  the  alcohol,  water,  or  NH4OH 
is  colored,  organic  coloring  matter  is  indicated. 

Total  Lead  and  Insoluble  Matter. — Treat 
I  g.  of  the  sample  with  15  cc.  of  HNO3  (1:1)  and 
sufficient  hydrogen  dioxide  to  dissolve  all  PbOs  on 
warming.  If  any  insoluble  matter  is  present,  add 
25  cc.  of  water,  boil,  filter  and  wash  with  hot  water. 
Insoluble  contains  free  SiOo,  and  should  be  examined 
for  BaS04  and  silicates,  if  appreciable.  To  original 
solution  or  filtrate  from  insoluble  add  20  cc.  of  con- 


^This  includes  orange  mineral. 


Appendix  I 


109 


centrated  H2SO4  and  evaporate  to  SO3  fumes;  cool, 
add  150  cc.  of  water  and  150  cc.  of  95  per  cent  ethyl 
alcohol,  let  stand  cold  two  hours,  filter  on  a  Gooch 
crucible,  wash  with  95  per  cent  alcohol,  dry  at  105° 
to  110°  C.  and  weigh  as  PbSOi.  Calculate  to  PbO. 
Red-lead  is  rarely  adulterated,  but  should  sample 
contain  soluble  barium  compounds,  the  PbSOi  ob- 
tained above  will  contain  BaS04.  In  this  case, 
digest  above  precipitate  with  acid  ammonium-acetate 
solution,  filter  off  BaSOi,  wash,  ignite  and  weigh 
BaSOi.  Calculate  to  BaO  or  BaCOa.  In  filtrate, 
determine  the  lead  as  PbS04  or  PbCr04.  If  sample 
contains  significant  amounts  of  calcium  or  mag- 
nesium, the  HNO3-H2O2  solution  is  boiled  till  all 
lead  is  converted  into  nitrate  and  then  lead  deter- 
mined as  PbCr04.  If  Ca  and  Mg  are  to  be  deter- 
mined, separate  lead  as  PbS  and  proceed  as  under 
basic  sulfate  of  lead  in  presence  of  these  metals. 

Determination  of  Lead  Peroxide  (PbOo) 
AND  True  Red-Lead  (Pb304). —  (Method  of 
Diehl,^  modified  by  Topf^ — not  applicable  when 
substances  are  present,  other  than  oxides  of  lead, 
that  liberate  iodine  under  conditions  given.) 

Weigh  I  g.  of  finely  ground  sample  into  a  200 
cc.  Erlenmeyer  flask,  add  a  few  drops  of  distilled 
water  and  rub  the  mixture  to  a  smooth  paste  with 
a  glass  rod  flattened  on  end.  Mix  in  a  small  beaker 
30  g.  of  c.  p.  'Tested  Purity''  crystallized  sodium 
acetate,  2.4  g.  of  c.  p.  potassium  iodide,  10  cc.  of 

2Dmgl.  polyt.  Jour.,  Vol.  246,  p.  196. 

^Zeitschrift  fiir  analytische  Chemie,  Vol.  26,  p.  296. 


no       Red- Lead  and  How  to  Use  it  in  Paint 


water  and  lo  cc.  of  50  per  cent  acetic  acid;  stir 
until  all  is  liquid,  warming  gently;  if  necessary,  add 
2  to  3  cc.  of  H2O,  cool  to  room  temperature  and 
pour  into  the  flask  containing  the  red-lead.  Rub 
with  the  glass  rod  until  nearly  all  the  red-lead  has 
been  dissolved;  add  30  cc.  of  water  containing  5 
or  6  g.  of  sodium  acetate,  and  titrate  at  once  with 
decinormal  sodium  thiosulfate,  adding  the  latter 
rather  slowly  and  keeping  the  liquid  constantly  in 
motion  by  whirling  the  flask.  When  the  solution 
has  become  light  yellow,  rub  any  undissolved  par- 
ticles up  with  the  rod  until  free  iodine  no  longer 
forms;  wash  off  rod,  add  the  sodium-thiosulfate 
solution  until  pale  yellow,  add  starch  solution  and 
nitrate  until  colorless,  add  decinormal  iodine  solu- 
tion until  blue  color  is  just  restored,  and  subtract 
the  amount  used  from  the  volume  of  thiosulfate  that 
had  been  added. 

Calculation. — The  Iodine  value  of  the  sodium- 
thiosulphate  solution  multiplied  by  0.941 93  =  PbO.; 
the  iodine  value,  multiplied  by  2.69973  =  Pb304 ;  the 
PbOs  value,  multiplied  by  2.866 i6=Pb304. 

The  Sodium-Thiosulfate  Solution  (decinor- 
mal).— Dissolve  24.83  g.  of  c.  p.  sodium  thiosulfate, 
freshly  pulverized  and  dried  between  filter  paper, 
and  dilute  with  water  to  i  liter  at  the  temperature 
at  which  the  titrations  are  to  be  made.  Solution 
best  made  with  well-boiled  HoO  free  from  COo,  or 
let  stand  8  to  14  days  before  standardizing.  Stand- 
ardize with  pure,  resublimed  iodine,  as  described  in 
Treadwell-Hall,  ''Analytical  Chemistry,"  Vol.  II, 


Appendix  I 


III 


p.  602  (1910),  and  also  against  pure  potassium 
iodate.  The  two  methods  of  standardization  should 
agree  within  o.i  per  cent  on  iodine  value. 

Starch  Solution. — Two  or  three  grams  of 
potato  starch  are  stirred  up  with  100  cc.  of  i  per 
cent  salicylic-acid  solution,  and  the  mixture  is  boiled 
till  starch  is  practically  dissolved,  then  diluted  to 
I  liter,*  or  as  per  Lord.^ 

Zinc. — If  in  appreciable  amount,  determine  in  fil- 
trate from  total  lead  as  per  methods  under  zinc 
white,  evaporating  off  the  alcohol. 

Water-Soluble. — Digest  10  g.  of  sample  with 
200  cc.  of  hot  water  on  steam  bath  for  one  hour; 
filter  on  an  11 -cm.  S.  &  S.  blue-ribbon  paper  and 
wash  with  hot  water  till  no  residue  is  left  on 
evaporating  a  few  drops  of  the  washings.  Evaporate 
filtrate  to  dryness  on  steam  bath  in  a  weighed  dish, 
dry  30  minutes  at  105°  C,  cool  and  weigh.  Take 
up  with  water  and  if  alkaline,  titrate  with  o.i  normal 
acid  and  methyl  orange;  calculate  to  NasCOs.  An- 
other lot  of  water-soluble  matter  is  tested  for 
nitrates,  nitrites,  carbonates,  sulfates,  sodium  and 
lead. 

Total  Silica. — Digest  5  g.  of  the  sample  In  a 
covered  casserole  with  5  cc.  of  HCl  and  15  cc.  of 
HNO3  (1:1).  Evaporate  to  dryness  to  dehydrate. 
Cool,  treat  with  hot  water  and  HNO3,  boil,  filter, 

^Lead  Peroxide. — If  sample  contains  an  appreciable  amount  of 
nitrite  (nitrate  has  no  effect  on  method),  leach  out  water-soluble  matter 
as  below,  dry  residue,  and  determine  PbO  as  above,  calculating  to 
basis  of  original  sample. 

^Notes  on  Metallurgical  Analysis,  p.  103  (1903). 


112       Red-Lead  and  How  to  Use  it  in  Paint 


wash  with  hot  acid  ammonium-acetate  solution,  then 
dilute  HCl  and  finally  hot  water.  Ignite  and  weigh 
as  SiOs.  The  residue  may  be  treated  with  H2SO4 
and  HF  in  cases  of  doubt  as  to  purity. 

Carbon  Dioxide. — Determined  by  evolution 
method,  using  dilute  HCl  and  stannous  chloride. 

Soluble  Sulp^ate. — Determined  as  under  basic 
sulfate  of  lead. 

Iron  Oxide. — Determined  by  Schaeffer's^  modi- 
fication of  Thomson's  colorimetric  method;  or,  in  a 
large  beaker,  treat  20  g.  of  the  sample  with  20  cc. 
of  water,  20  cc.  of  HNO3  (sp.  gr.  1.4)  and  3  cc. 
of  formaldehyde  solution.  Warm  till  all  PbOs  is 
dissolved,  dilute  with  water,  warm,  filter  off  in- 
soluble and  wash  with  hot  water.  Ignite  filter  and 
insoluble,  evaporate  with  H2SO4  and  hydrofluoric 
acid.  To  filtrate  from  insoluble  add  14  cc.  of  H2SO4 
(1:1),  filter  off  PbSOi,  wash.  Residue  from  HF 
and  H2SO4  is  dissolved  in  H2SO4  and  added  to 
filtrate  from  PbS04;  dilute  to  500  cc.  and  determine 
Fe  colorimetrically  in  an  aliquot,  using  same  amounts 
of  HNO3,  H2SO4  and  formaldehyde  in  comparison 
solution/     Calculate  to  Fe203. 

^Journal  of  Industrial  and  Engineering  Chemistry,  Vol.  4,  p.  659, 
(1912). 

^Chemisch-technische  Untersuchungs-Methoden,  Lunge,  Berl.,  Bd.  2, 
S.  95,  6th  Ed. 


114       Red-Lead  and  How  to  Use  it  in  Paint 


Determination  of  Pb304 
(National  Lead  Company  Laboratory) 

1.  ^'Red-Lead  Solution.'' — Weigh  out  into  a 
1300  c.  cm.  beaker,  600  grammes  c.  p.  crystalline 
sodium  acetate  and  48  grammes  c.  p.  potassium 
Iodide.  Make  up  a  solution  of  25  per  cent  acetic 
acid,  by  mixing  150  c.  cm.  c.  p.  glacial  acetic  acid 
with  450  c.  cm.  distilled  water.  Now  pour  about 
500  c.  m.  of  this  25  per  cent  acid  Into  the  1300 
c.  cm.  beaker,  above  mentioned,  reserving  the  re- 
mainder. Warm  the  beaker  on  the  steam-bath, 
stirring  occasionally,  until  a  clear  solution  Is  ob- 
tained. Cool  this  solution  to  room  temperature,  and 
pour  It  into  a  i-lltre  graduated  flask.  Then  add 
enough  of  the  reserved  25  per  cent  acetic  acid  to 
make  exactly  1000  c.  cm.  and  mix  thoroughly. 

2.  One-Tenth  N  Sodium  Thiosulphate 
Solution. — Weigh  out  Into  a  large  beaker  25 
grammes  c.  p.  crystalline  sodium  thiosulphate;  add 
400-500  c.  cm.  distilled  water,  and  stir  until  dis- 
solved. Wash  this  solution  Into  a  i-litre  graduated 
flask,  make  up  to  the  mark  with  distilled  water,  and 
mix  thoroughly. 

Each  c.  cm.  of  this  solution  Is  equivalent  to  about 
3.48  per  cent  true  red-lead  (using  i-gramme  charge) , 
but  Its  exact  value  should  be  determined  by  standard- 
izing against  pure  iodine  or,  better,  against  a  stand- 
ard sample  of  red-lead,  the  ^'true  red-lead"  content 


Appendix  I 


IIS 


of  which  IS  accurately  known.  The  strength  of  this 
solution  gradually  decreases  upon  standing.  It  is  a 
good  plan,  therefore,  when  analyzing  a  sample  of 
red-lead,  to  run  a  parallel  determination  with  the 
standard  red-lead,  thus  ascertaining  the  exact 
strength  of  the  thiosulphate  solution.  This  pro- 
cedure consumes  but  little  extra  time  and  will  often 
prevent  error. 

3.  Starch-Indicator  Solution. — Weigh  out 
y2  gramme  of  ordinary  starch  into  a  small  beaker, 
add  IOC  cm.  cold  distilled  water,  and  mix  to  a  thin 
paste.  Measure  into  another  beaker  100  c.  cm. 
distilled  water,  heating  to  boiling,  and  pour  into  it 
slowly,  with  constant  stirring,  the  previously  pre- 
pared starch  paste.  Then  boil  for  two  minutes, 
with  constant  stirring.  This  solution  does  not  keep 
well  and  should  be  prepared  fresh  for  each  day's 
work. 

Method. — Weigh  i  gramme  of  sample  into  a 
300  c.  cm.  Erlenmeyer  flask.  Add  a  few  drops  of 
distilled  water  and  rub  the  mixture  to  a  smooth 
paste  with  a  glass  rod.  Th  jn  add  50  c.  cm.  of  the 
^'red-lead  solution''  and  continue  rubbing  with  the 
glass  rod  until  nearly  all  the  red-lead  has  been  dis- 
solved. Remove  the  rod  from  the  solution  and  wash 
it  off  with  25  c.  cm.  of  distilled  water,  making  sure 
that  all  washings  run  into  the  flask.  Titrate  at  once 
with  the  one-tenth  N  thiosulphate,  adding  the 
latter  rather  slowly  and  keeping  the  liquid  constantly 
in  motion  by  whirling  the  flask.  When  the  color  of 
the  assay  has  been  reduced  to  a  light  yellow,  ex- 


Ii6       Red-Lead  and  How  to  Use  it  in  Paint 

amine  it  carefully  for  undissolved  particles  of  red- 
lead.  If  present,  they  can  often  be  dissolved  by 
shaking  the  flask  for  a  short  time,  but  if  they  dissolve 
too  slowly,  they  should  be  crushed  by  rubbing  again 
with  the  glass  rod,  until  completely  dissolved.  The 
rod  should  then  be  removed  and  washed  with  a  few 
cubic  centimeters  of  water.  After  the  addition  of 
thiosulphate  has  reduced  the  color  of  the  assay  to 
a  very  pale  lemon  tint  and  care  has  been  taken  to 
see  that  solution  of  the  red-lead  is  complete,  add 
2  c.  cm.  of  the  starch-indicator  solution.  The  assay 
should  then  turn  blue.  Now  finish  the  titrating  by 
adding  the  thiosulphate  solution,  drop  by  drop,  shak- 
ing the  flask  very  thoroughly  after  each  addition, 
until  the  blue  color  disappears. 

Calculation. — Suppose,  for  instance,  that  a 
red-lead  sample,  by  this  method,  requires  24.8  c. 
cm.  of  thiosulphate  solution,  and  that  the  laboratory 
standard  red-lead  requires  26.5  c.  cm.  of  thio- 
sulphate. 

Then  the  per  cent  ''true  red-lead''  in  the  sample  is : 
92.00 

~  X24.8  =  86.7  per  cent  "true  red-lead." 

26.5  '  ^ 

Notes. — Before    analyzing    a    coarse  sample, 

''glassmakers'  red-lead,"  for  instance,  it  is  necessary 

to  grind  the  sample,  thus  rendering  it  more  readily 

soluble. 

Never  attempt  to  hasten  solution  of  the  sample  by 
warming,  as  this  will  cause  loss  of  iodine,  and,  con- 
sequently, too  low  a  result.  The  "red-lead  solution" 
should  be  kept  in  a  cool,  dark  place,  but  even  then, 


Appendix  I 


117 


however,  It  may  gradually  decompose,  with  liber- 
ation of  iodine.  The  error  thereby  introduced,  in  a 
determination,  is  not  appreciable  if  the  thiosulphate 
is  freshly  standardized,  before  use,  against  a  stand- 
ard sample  of  red-lead,  as  recommended. 

The  main  consideration,  in  this  method,  is  to  see 
that  the  determination  is  run  in  exactly  the  same  way, 
and  under  exactly  the  same  conditions,  as  the 
standardization  of  the  thiosulphate,  by  means  of  the 
standard  sample  of  red-lead.  Then  any  small  errors 
in  the  determination  will  be  offset  by  similar  errors 
in  the  standardization. 


FORMULAS 

Red,  for  First  Coat 

100  lbs.  Dutch  Boy  Paste  Red 
Lead 

2.5  gals,  linseed  oil  (measured) 
I  pint  turpentine 
I  pint  drier 

4.85  gallons  of  paint 


Light  Brown,  for  Second  Coat 

100  lbs.  Dutch  Boy  Paste  Red 
Lead 

^4  lbs.  paste  lampblack 
2.65  gals. linseed  oil  (measured) 
1  pint  turpentine 
I  pint  drier 

5.1  gallons  of  paint 


Gray,  for  Light  Finish 

One  coat  covers  over  Red 
100  lbs.  Paste  White  Lead 
4  oz.  paste  lampblack 
8  oz.  paste  French  ochre 
4  gals,  linseed  oil  (measured) 
1  pint  turpentine 
1  pint  drier 

7  gallons  of  paint 


Dark  Brown,  for  Third  Coat 

100  lbs.  Dutch  Boy  Paste  Red 
Lead 

6  lbs.  paste  lampblack 
3.64  gals,  linseed  oil  (measured) 
1  pint  turpentine 
I  pint  drier 

6.67  gallons  of  paint 


Dark  Green 

100  lbs.  Dutch  Boy  Paste  Red 
Lead 

I2V2  lbs.  paste  chrome  yellow 

medium 
7H  lbs.  paste  Prussian  blue 
4.54  gals,  linseed  oil  (measured) 
1  pint  turpentine 
I  pint  drier 

8. 1  gallons  of  paint 


Black 

100  lbs.  Dutch  Boy  Paste  Red 
Lead 

52  lbs.  paste  lampblack 
1 6  lbs.  paste  Prussian  blue 
1 5.2  gals,  linseed  oil  (measured) 
1  gal.  turpentine 
1  gal.  drier 

26.5  gallons  of  paint 


DUTCH  BOY  PASTE  R 

of  l.insced  Oil 

i 
i 

11 

:l 
II 
il 

;s 
il 

il 

il 

il 
il 

iii 
iii 

il 

ii 
il 
il 

il 

ii 

B 

li 

iii 

i 

Vd 

1 

ii 
1 
1 

ii:i 

i 

il 

i!:i 
U 
ii:i 
ii 

I 
I 

i 

i! 
i 
\ 
1 

-.3 

m 

m 

WEIGH 

OF  PIGMENT  I 

•1: 

1:  i; 

..l,.„.I.. 

■  i:i  is 

ill 

^9  3;- 

11 

1 

11 

1 

1! 

1 

1 

1 

•56 

1 

1 

1 

1 

1 

■i 

'11 

1 

111 

68  I. 75 

i8.6 

2.98 

it: 

.3 

■57 

... 

.78 

:8: 

■8s 

:ll 
.89 

.93 

;;^3  : 

S  1-73   l-Sl  I 

It 

79  1.86 
\:Ts 

88  1.96 

9     1.67  1.86 

11° 

!  ;:2  i:S 

08  It 

in 

■78s 

.63 

.84 
it 

;:S 

HANDY  TABLE  OF  RED-LEAD  DATA,  USING  ENGLISH  (OR  IMPERIAL)  GALLONS 

TABLE  III— (Engush) 

BASED  ON  DRY  RED-LEAD  FORMULAS  WITH  DUTCH  BOY  PASTE  RED-LEAD  EQUIV/U,ENTS 


FOR  AN  IMPERIAL  G.\LLaN  OF 

N  OF  PAINT 

■IS- 

Pas^eRed-liad 

Red-Lead'i?Each 
Imperial  Gallon 

ill 

is 

(PINTS) 

i 

;! 

:! 

ii 

i 

1 

i 

1 

1 

i 

48 

39-6 

i 

:i 

8 

■  ii 

1 

ii 

;i 

jSo 
.53.  S 

11 

4-84 

i 

ii 

Ii 

Si 

'1 

i 

I 

i:i 

ii 

S 

i:i 

I: 

Ii 

1 

i 

i 

f 


F  PIGMENT  IN  A 


SHILLINGS  AND  PENCE 


11 
t 


rill" 


1 1 


ill 

I'll, 


1" 

iill 


11 


ill 


i 


i 


I 


III 


ill 


1 
:i 
:i 
I 


APPENDIX  II 


SPECIFICATIONS  FOR  PAINTING 
BRIDGES 

Three  Coats  on  Nezv  Bridges 

1.  Before  leaving  the  shops  all  structural  metal 
shall  be  cleaned  of  all  mill  scale  that  can  be  scraped 
off  and  of  all  dirt,  rust  and  oil,  and  receive  one  coat 
of  pure  red-lead  and  linseed  oil  paint  as  specified  in 
paragraph  No.  4.  This  shall  be  dry  to  the  touch 
before  the  metal  is  shipped.  All  surfaces  which  will 
be  inaccessible  after  erection  (field  riveted  and 
bolted  joints)  shall  have  a  specially  heavy  coat. 

2.  After  erection  all  structural  metal  shall  be 
cleaned  to  the  satisfaction  of  the  inspector.  All 
abraded  or  unpainted  surfaces  shall  be  painted. 
When  this  paint  is  dry  the  entire  surface  shall  re- 
ceive one  coat  of  pure  red-lead  and  oil  paint,  mixed 
as  specified  in  paragraph  No.  4,  to  which  has  been 
added  two  ounces  of  paste  lampblack  to  each  gallon 
of  paint. 

2a.  After  erection  and  before  the  first  field  coat 
as  specified  above,  all  rivet-heads  and  bolt-heads 
shall  be  painted  an  extra  coat,  and  so  also  shall  be  all 

119 


I20 


Red-Lead  and  How  to  Use  it  in  Paint 


edges  and  angles  to  a  distance  of  an  inch  from  the 
edge.  After  drying,  the  first  full  field  coat,  as 
specified  in  paragraph  No.  2,  shall  be  applied  over 
the  whole. 

3.  At  least  a  week  shall  elapse  before  another 
coat  of  paint  is  applied.  If  a  dark  color  is  desired, 
the  bridge  shall  receive  a  coat  of  paint  as  specified 
in  paragraph  No.  4,  with  the  addition  of  one  pound 
of  paste  lampblack  to  each  gallon  of  paint;  but  if  a 
light  color  is  desired,  the  third  coat  shall  be  made  by 
mixing  100  pounds  of  pure  basic  carbonate  whlte- 
lead-in-oil  (paste)  with  four  ounces  of  paste  lamp- 
black, eight  ounces  of  paste  French  ochre,  four  gal- 
lons of  pure  raw  linseed  oil,  one  pint  of  pure  turpen- 
tine, and  one  pint  of  drier,  free  from  rosin;  this 
latter  formula  makes  about  seven  gallons  of  paint. 

4.  The  red-lead  to  be  used  shall  contain  not  less 
than  94  per  cent  of  pure  red-lead  (PbsOi)  and  not 
more  than  one-half  of  one  per  cent  of  materials 
other  than  oxide  or  carbonate  of  lead;  and  not  less 
than  99  per  cent  shall  wash  through  a  sieve  of  200 
meshes  to  the  linear  inch.  If  the  red-lead  is  pur- 
chased dry  it  shall  be  mixed  in  the  proportion  of  28 
pounds  of  pigment  to  one  gallon  of  pure  raw  linseed 
oil;  and  if  paste  red-lead  is  used,  40  pounds  of  such 
paste,  containing  only  pure  red-lead  and  6  to  7  per, 
cent  of  linseed  oil,  with  one  gallon  of  pure  linseed 
oil,  and  to  a  gallon  of  paint  may  be  added  at  the 
discretion  of  the  master  painter  or  of  the  inspector 
one-third  of  a  pint  of  turpentine  and  one-third  of  a 
pint  of  drier  free  from  rosin. 


Appendix  II 


121 


Two  Coats  on  New  Bridges 

1.  Before  leaving  the  shops  all  structural  metal 
shall  be  cleaned  of  all  mill  scale  that  can  be  scraped 
off  and  of  all  dirt,  rust  and  oil,  and  receive  one  coat 
of  pure  red-lead  and  linseed  oil  paint  as  specified  in 
paragraph  No.  3.  This  shall  be  dry  to  the  touch 
before  the  metal  is  shipped.  All  surfaces  which  will 
be  inaccessible  after  erection  (field  riveted  and 
bolted  joints)  shall  have  a  specially  heavy  coat. 

2.  After  erection  all  structural  metal  shall  be 
cleaned  to  the  satisfaction  of  the  inspector.  All 
abraded  or  unpainted  surfaces  shall  be  painted. 
When  this  paint  is  dry,  if  a  dark  co^or  is  desired,  the 
bridge  shall  receive  a  coat  of  paint  as  specified  in 
paragraph  No.  3,  with  the  addition  of  one  pound  of 
paste  lampblack  to  each  gallon  of  paint;  but  if  a 
light  color  is  desired,  the  second  coat  shall  be  made 
by  mixing  100  pounds  of  pure  basic  carbonate  white- 
lead-in-oil  (paste)  with  four  ounces  of  paste  lamp- 
black, eight  ounces  of  paste  French  ochre,  four  gal- 
lons of  pure  raw  linseed  oil,  one  pint  of  pure  turpen- 
tine, and  one  point  of  drier,  free  from  rosin;  this 
latter  formula  makes  about  seven  gallons  of  paint. 

2a.  After  erection  and  before  the  first  field  coat  as 
specified  above,  all  rivet-heads  and  bolt-heads  shall 
be  painted  an  extra  coat,  and  so  also  shall  be  all 
edges  and  angles  to  a  distance  of  an  inch  from  the 
edge.  After  drying,  the  field  coat,  as  specified  in 
paragraph  No.  2,  shall  be  applied  over  the  whole. 


122       Red-Lead  and  How  to  Use  it  in  Paint 


3.  The  red-lead  to  be  used  shall  contain  not  less 
than  94  per  cent  of  pure  red-lead  (Pb304)  and  not 
more  than  one-half  of  i  per  cent  of  materials 
other  than  oxide  or  carbonate  of  lead;  not  less  than 
99  per  cent  shall  wash  through  a  sieve  of  200  meshes 
to  the  linear  inch.  If  the  red-lead  is  purchased  dry, 
it  shall  be  mixed  in  the  proportions  of  28  pounds  of 
pigment  to  one  gallon  of  pure  raw  linseed  oil;  and  if 
paste  red-lead  is  used,  40  pounds  of  such  paste,  con- 
taining only  pure  red-lead  and  6  to  7  per  cent  of 
linseed  oil,  with  one  gallon  of  pure  linseed  oil,  and 
to  a  gallon  of  paint  may  be  added  at  the  discretion  of 
the  master  painter  or  of  the  inspector  one-third  of  a 
pint  of  turpentine  and  one-third  of  a  pint  of  drier 
free  from  rosin. 


Repainting  Bridges 

All  rust  shall  be  thoroughly  removed  by  the  use  of 
substantial  steel  scrapers,  aided  by  hammering  if 
necessary,  and  then  wire-brushed.  All  dirt  and  loose 
paint  shall  be  cleaned  off.  Especial  care  shall  be 
taken  in  cleaning  the  part  under  the  deck  or  road- 
way. After  this,  all  exposed  metal  surfaces  shall 
have  a  coat  of  red-lead  paint  made  by  mixing  either 
28  pounds  of  dry  red-lead  or  40  pounds  of  paste  red- 
lead  with  one  gallon  of  pure  linseed  oil;  to  each  gal- 
lon of  such  paint  one-third  of  a  pint  each  of  turpen- 
tine and  drier  may  be  added.  When  this  is  dry,  the 
bridge  is  ready  for  repainting  and  may  receive  such 


Appendix  II 


123 


paint  as  maybe  specified;  such  as  are  described  In  the 
Specifications  for  Painting  Bridges.  Gates,  if  pres- 
ent, should  be  painted  a  distinctive  and  conspicuous 
color. 


The  surface  must  be  thoroughly  clean  and  free 
from  rust  and  loose  scale;  It  then  shall  receive  a  coat 
of  the  following  paint: 


If  It  Is  desired  to  use  three  coats,  the  second 
should  be  the  same  as  above  with  the  addition  of 
^  pound  paste  lampblack  to  the  above  formula; 
then  the  third  coat  (or  if  only  two  coats  are  desired, 
the  second  or  finishing  coat)  shall  be  as  follows: 


Exterior  Ship  Painting 


Paste  red-lead. 
Raw  linseed  oil 
Japan  drier .  .  .  . 
Turpentine .  .  .  . 


100  lbs. 
2\  gals, 
li  qts. 


4.8  gals. 


Paste  white-lead  (carbonate) 

Paste  French  ochre  

Paste  lampblack  

Pure  linseed  oil  

Turpentine  

Drier  (free  from  rosin)  


100  lbs. 


8  oz. 

4  " 
4  gals, 
ipt. 


7  gals. 


If  a  darker  gray  Is  desired,  more  lampblack  and 
ochre  may  be  added. 


Appendix  II 


125 


Interior  Ship  Painting 

After  thoroughly  cleaning  the  metal  surface,  it 
shall  be  painted  with  a  paint  made  as  follows: 

Paste  red-lea.d ..................  loo  lbs. 

Pure  linseed  oil   2  gals. 

Turpentine   J  " 

Drier   li  pts. 


4!  gals. 

When  this  is  thoroughly  dry  a  second  coat  shall  be 
applied  of  the  following  paint : 

Paste  white  lead  (carbonate)   100  lbs. 

Paste  French  ochre   8  oz. 

Paste  lampblack   4 

Pure  linseed  oil   3  gals. 

Turpentine   i  qt. 

Drier   pts. 


6  srals. 


This  Is  to  be  a  rather  heavy  full  coat. 

If  a  pure  white  is  desired,  a  third  coat  may  be 
applied  as  follows : 

Paste  white-lead  (carbonate)   100  lbs. 

Pure  linseed  oil   3  gals. 

Turpentine   i  qt. 

Drier   i\  pts. 


6  gals. 


Or  a  suitable  varnish  enamel  paint  may  be  used  for 
the  third  coat. 


126 


Red-Lead  and  How  to  Use  it  in  Paint 


Note. — The  second  coat,  as  above,  Is  a  light, 
warm  gray,  and  one  coat  covers  over  red-lead, 
whereas  no  pure  white  paint  will  do  this;  for  most 
places  it  is  light  enough  in  color,  and  it  makes  a  good 
foundation  for  any  paint. 

Specification  for  Painting  JVater-Tanks 

The  surface  shall  be  cleaned  as  thoroughly  as  pos- 
sible, first,  of  all  dirt,  oil  and  grease;  second,  of 
scale,  either  (a)  by  the  sand-blast  or  (b)  by  very 
thorough  scraping  and  wire-brushing.  It  shall  then 
be  painted  with  the  following  paint: 

For  the  interior,  mix  loo  pounds  paste  red-lead 
with  two  gallons  of  oil,  or  lOO  pounds  dry  red-lead 
(containing  not  less  than  95  per  cent  of  Pb304)  with 
three  gallons  of  oil;  the  oil  shall  be  pure  boiled  lin- 
seed oil  of  quality  acceptable  to  the  engineer;  to  this 
amount  of  red-lead  and  oil  mixture  shall  be  added 
8  pounds  of  fine  litharge,  mixed  in  i  pint  of  pure 
raw  linseed  oil  and  i  quart  of  pure  spirit  of  tur- 
pentine; this  mixture  of  red-lead,  litharge,  oil  and 
turpentine  is  the  paint  which  is  to  be  applied  to  the 
interior  only.  At  suitable  intervals  two  more  coats 
of  this  paint  shall  be  applied  to  the  Interior,  each  coat 
being  allowed  to  become  dry  and  hard  before  an- 
other coat  Is  applied.  If  the  tank  Is  so  formed  or 
situated  that  It  Is  not  well  ventilated,  this  shall  be 
effected  artificially  by  blowing  air  Into  It  in  sufficient 
quantity. 

For  the  exterior,  the  paint  shall  consist,  for  the 


Appendix  II 


127 


first  coat,  of  100  pounds  paste  red-lead  and  two  and 
a  half  gallons  of  raw  linseed  oil,  or  100  pounds  dry 
red-lead  (of  not  less  than  94  per  cent  of  Pb304)  and 
three  and  a  half  gallons  of  oil;  to  this  amount  of  red- 
lead  and  oil  may  be  added  one  and  a  half  pints  each 
of  drier  and  turpentine,  if  desired. 

For  the  second  coat,  to  a  similar  red-lead  paint 
three-quarters  of  a  pound  of  paste  lampblack  may 
be  added;  and  for  the  third  coat,  100  pounds  of 
paste  white-lead  (carbonate),  8  ounces  of  paste 
French  ochre,  4  ounces  of  paste  lampblack,  4  gallons 
of  raw  linseed  oil,  i  pint  of  drier  and  i  pint  of 
turpentine. 

Painting  Gas-Holders 

The  paint  specified  for  water-tank  interiors  will  be 
found  suitable  for  the  under  coats  of  gas-holders,  but 
if  thought  desirable  it  may  be  thinned  somewhat  with 
turpentine;  i  quart  of  additional  turpentine  being 
sufl^Lcient  for  the  quantity  of  paint  already  mentioned. 
The  finishing  coat  should  be  like  the  light  gray  finish- 
ing coat  for  water-tanks. 

Architects^  Painting  Specifications  for  All  Iron^  Steel 
and  Other  Metal  Work 

I.  Structural  Iron  and  Steel  Before  Erec- 
tion.— Before  leaving  the  shops  all  structural  iron 
and  steel  work  shall  be  cleaned  of  all  loose  mill  scale, 


128       Red-Lead  and  How  to  Use  it  in  Paint 


dirt,  rust  and  oil  and  receive  one  coat  of  pure  red- 
lead  and  linseed  oil  paint  as  specified  in  paragraph 
No.  5.  All  surfaces  which  shall  be  inaccessible  after 
erection  shall  receive  two  coats  of  the  same  paint 
before  erection. 

2.  Structural  Iron  and  Steel  After  Erec- 
tion.— All  structural  iron  and  steel  shall  be  cleaned 
after  erection.  If  there  are  any  abrasions  in  the 
paint,  they  shall  be  repainted  with  the  paint  specified 
above,  after  removing  all  foreign  substances  with  a 
stiff  wire  brush.  After  retouched  places  have  dried, 
the  entire  surface  shall  receive  one  coat  of  pure  red- 
lead-in-oil,  mixed  as  specified  in  paragraph  No.  5 
with  the  addition  of  2  ounces  of  lampblack  in  oil  to 
each  gallon  of  paint.  Where  the  iron  or  steel  is  to 
be  exposed  add  a  third  coat  of  red-lead-in-oil  mixed 
as  specified  in  paragraph  No.  5,  with  the  addition 
of  I  pound  of  lampblack  in  oil  to  each  gallon  of 
paint. 

3.  Interiorly  Exposed  Metal. — All  interiorly 
exposed  metal  such  as  pipes,  automatic  sprinklers, 
steam  and  hot  water  radiators,  elevator  shafts  and 
stairways,  shall  receive  two  coats  of  pure  red-lead 
and  oil  mixed  as  specified  in  paragraph  No.  5. 
Where  the  color  of  the  red-lead  does  not  conform 
to  the  color  scheme,  pure  basic  carbonate  white-lead 
and  oil  paint  tinted  as  desired  shall  be  applied  over 
the  red-lead  paint. 

4.  Exteriorly  Exposed  Metal. — All  exteriorly 
exposed  metal  surfaces  such  as  tin,  galvanized  iron, 
iron  and  steel,  cast  iron,  iron  or  steel  used  in  roof- 


.Appendix  11 


129 


ing,  cornices,  valleys,  gutters,  down-spouts,  railings, 
gratings,  fire  escapes,  smoke  stacks,  etc.,  shall 
receive  two  coats  of  pure  red-lead  and  oil  paint, 
mixed  as  specified  In  paragraph  No.  5.  Where  the 
color  of  the  red-lead  does  not  conform  to  the  color 
scheme,  pure  basic  carbonate  white-lead  and  oil  paint 
tinted  as  desired  shall  be  applied  over  the  red-lead 
paint.  All  metal  roofings.  Including  valleys,  shall 
receive  one  heavy  coat  of  pure  red-lead  and  oil  paint 
on  the  under  surface,  mixed  as  specified  In  paragraph 
No.  5. 

5.  Formula  for  Mixing  Red-Lead  with  Oil. 
— The  red-lead  to  be  used  shall  contain  not  less  than 
94  per  cent  of  true  red-lead  (PbsOi)  and  not  more 
than  one-half  of  i  per  cent  of  materials  other  than 
oxide  or  carbonate  of  lead;  and  not  less  than  99  per 
cent  shall  wash  through  a  sieve  of  200  meshes  to  the 
linear  Inch.  If  the  red-lead  Is  purchased  dry  It  shall 
be  mixed  (preferably  by  grinding  In  a  mill)  with 
pure  raw  linseed  oil,  conforming  to  the  specifications 
of  the  American  Society  for  Testing  Materials,  In 
the  proportion  of  28  pounds  of  pigment  to  one  gal- 
lon of  oil;  to  each  gallon  of  such  paint  may  be  added 
at  the  discretion  of  the  master  painter  or  of  the 
inspector  not  more  than  one-third  pint  of  pure  tur- 
pentine japan  drier;  and  If  red-lead  ground  In  oil  Is 
purchased.  It  shall  contain  nothing  but  pure  red-lead 
and  pure  linseed  oil  agreeing  with  the  above  speci- 
fication, and  shall  be  mixed  with  linseed  oil  and  drier 
In  proportions  of  40  pounds  of  Dutch  Boy  reddead- 
in-oll  to  I  gallon  of  pure  raw  linseed  oil. 


130       Red-Lead  and  How  to  Use  it  in  Paint 


Notes 

The  U.  S.  Navy  and  U.  S.  Engineers'  specification 
for  red-lead  Is  followed  In  these  specifications,  and 
calls  for  dry  red-lead  containing  not  less  than  94  per 
cent  PbsO^,  or  paste  made  from  red-lead  of  not  less 
than  97  per  cent  PbsO^  with  a  content  of  6  to  7  per 
cent  raw  oil. 

This  red-lead  specification  is  rather  elaborate.  If 
paste  red-lead  is  used  the  following  will  be  adequate: 

The  paste  shall  contain  only  red-lead  and  6  to 
7  per  cent  of  linseed  oil,  and  shall  be  guaranteed 
for  three  months  against  hardening  If  kept  sealed  In 
the  original  package  at  ordinary  temperature. 

But  if  dry  red-lead  Is  used  it  is  at  least  necessary 
to  specify  the  per  cent  of  Pb304;  if  this  is  sufficiently 
high  It  Is  sure  to  be  fine  and  pure;  the  U.  S.  Navy 
and  U.  S.  Engineers  Insist  on  not  less  than  94  per 
cent. 

The  American  Society  for  Testing  Materials  has 
a  specification  for  North  American  raw  linseed  oil 
which  calls  for  sp.  g.  at  15°  C.  from  0.936  to  0.932, 
acid  No.  not  over  6,  saponification  No.  195  to  189, 
Iodine  No.  (Hanus)  not  less  than  180.  (South 
American  oil  may  have  the  iodine  number  as  low  as 
170.)  A  good  specification  for  linseed  oil  is  that 
It  shall  agree  with  the  specification  of  the  American 
Society  for  Testing  Materials,  shall  be  aged  at  least 
one  month,  and  a  sample  after  standing  twenty-four 
hours  In  a  graduated  cylinder  at  a  temperature  of  not 
less  than  70°  F.  shall  not  show  more  than  one  and  a 


Appendix  II 


131 


half  per  cent  of  sediment,  by  volume.  A  specification 
calling  for  pure,  well-settled  linseed  oil  would  prob- 
ably be  sufficient  in  law. 

The  A.  S.  T.  M.  specification  for  boiled  linseed 
oil  names  sp.  g.  at  15.5°  C.  to  be  0.945  to  0.937,  ^^i^ 
No.  not  over  8,  sapon.  No.  195-189,  iodine  No. 
(Hanus)  not  under  178,  manganese,  not  under  0.03, 
lead,  not  under  o.i,  calcium,  not  over  0.3. 

It  is  to  be  noted  that  in  these  specifications  for  new 
work  it  is  said  that  all  loose  scale  shall  be  removed. 
A  much  more  thorough  cleaning  is  sometimes  in- 
sisted on  by  the  use  of  the  sand-blast.  Several  rail- 
roads and  some  muncipalities  use  the  sand-blast  for 
cleaning  old  bridges,  either  in  whole  or  in  part,  but 
such  work  is  not  here  included. 

In  the  ^'new  bridge"  specification  the  paragraph 
2a  may  be  struck  out,  if  thought  best;  but  it  is  prac- 
tised by  some  of  the  best  engineers.  Rivet-heads  and 
angles  always  rust  first,  and  it  is  prudent  and  eco- 
nomical to  give  them  an  extra  coat  when  new.  This 
is  especially  important  in  case  of  two-coat  work;  two 
coats  are  not  enough. 

The  white-lead,  ochre  and  lampblack  paint  recom- 
mended is  a  light  stone  color,  and  one  heavy  coat  will 
cover  over  red-lead;  it  is  standard  in  one  or  two 
states  and  is  practically  what  is  used  on  the  New 
York  City  bridges  for  an  outside  coat  over  red-lead. 
No  adulteration  of  the  white-lead  should  be  allowed 
or  the  red-lead  will  show  through. 

Paste  paints  should  be  thinned  as  follows: 

At  first  a  little  oil  is  added  to  the  paste,  and 


132        Red-Lead  and  How  to  Use  it  in  Paint 


worked  into  it  with  a  paddle;  then  add  a  little  more 
oil,  and  so  on  until  it  is  of  the  required  consistency. 
Where  paste  colors  are  used  for  tinting,  these  are 
separately  thinned  with  part  of  the  oil  in  the  same 
manner  and  finally  mixed  together.  It  is  also  good 
practise  to  pour  the  finished  product  through  a  fine 
sieve  or  cheese-cloth.  All  professional  painters  are 
familiar  with  these  methods. 

All  cavities  which  may  fill  with  water  should  be 
drained,  or  filled  with  cement;  this  is  not  a  matter 
for  the  painter;  but  paint  will  not  give  much  protec- 
tion to  surfaces  which  are  exposed  to  ice,  and  to 
freezing  and  thawing. 

Painting  bridges  which  are  not  thoroughly  cleaned 
is  a  waste  of  material  and  labor.  In  painting  high- 
way bridges  particular  attention  should  be  given  to 
the  metal  immediately  under  the  planking;  and  if  the 
ends  of  the  planks  impinge  against  metal  members, 
such  places  are  apt  to  rust.  The  use  of  salt  on  side- 
walks or  roadways  for  removing  ice  is  also  a  source 
of  danger.  In  all  painting  it  is  essential  to  use  good 
brushes  and  no  brush  more  than  4  inches  wide  is 
advisable;  also,  the  use  of  a  brush  fixed  to  a  handle 
several  feet  long  should  be  prohibited;  such  a  con- 
trivance is  sometimes  called  by  the  painters  a  ^*man- 
helper." 

In  any  or  all  of  the  foregoing  formulas,  raw  lin- 
seed oil  may  be  changed  to  a  mixture  of  one-third  to 
one-half  boiled  oil  and  the  remainder  raw  oil,  in 
which  case  the  drier  should  be  left  out,  but  may  be 
replaced  by  an  equal  amount  of  turpentine. 


Appendix  II 


133 


The  formulas  in  this  book  are  based  on  the  U,.  S. 
gallon,  and  if  the  book  comes  into  use  by  readers 
who  use  the  English  or  imperial  gallon  (which  is 
one-fifth  larger)  the  amount  of  red-lead  should  be 
increased  one-fifth,  and  the  surface  covered  is  cor- 
respondingly more.  Two  tables  will  be  found  giving 
formulas  and  prices  in  English  units;  but  these  Eng- 
lish formulas  are  not  the  equivalent  of  the  appar- 
ently similar  U.  S.  formulas,  because  while  the 
pounds  are  the  same  pounds  the  gallons  are  larger 
gallons,  hence  a  given  number  of  pounds  of  pigment 
to  a  gallon  of  oil  (or  paint)  makes  thinner  paint 
than  that  made  on  the  United  States  formulas.  Thus 
a  paint  made  on  the  basis  of  28  pounds  of  dry  red- 
lead  to  the  United  States  gallon  of  oil  would  be  the 
same  paint  as  if  made  of  33.6  pounds  to  one  imperial 
gallon  of  oil,  and  of  course  this  33.6  pounds  of  red- 
lead  plus  I  imperial  gallon  of  oil  makes  1.38  im- 
perial gallons  of  paint  the  same  as  28  pounds  plus  a 
gallon  of  oil  makes  1.38  gallons  of  paint  in  United 
States  measures.  This  is  shown  in  the  tables,  in 
which  some,  but  not  all,  of  these  relations  are 
exhibited. 


INDEX 


PAGE 

Architects'  specifications   127 

Area  covered  91,  94,  loi 

Automobiles   61 

Brushes  74,  132 

Brush  marks  7,  14,  29 

Bridge,  Havre-de-Grace   45 

—  Hell-Gate   28 

— ,  Louisville  ,  44,  48,  56,  57 

— ,  Nickel-plate  R.R   91 

Cleaning  surfaces  66,  68,  69 

Cost  of  paint   78 

Costs  18,  32,  39,  42 

Cracks  and  checks   24 

Density  of  materials   76 

Drier  87,  90 

Elastic-undercoat  cracks   24 

Gallon,  trade  of  oil   loi 

Havre-de-Grace  bridge   45 

Hell-Gate  bridge   28 

Highway  bridges  ix,  32,  67 

 color  of  32,  34 

Illusions  in  regard  to  paint  3  7>  3 9>  43 >  73 

Inhibition  of  rusting  43>  46 


135 


136  Index 

PAGE 

Labor-cost   32 

Lampblack  20,  30,  86 

—  how  to  mix  with  paint  20,  86 

—  paste  20,  86 

Linseed  oil,  attraction  for  red-lead  and  white-lead„   12 

—  boiled  i9>  53j  56 

—  extraction  from  paint   12 

—  proportion  in  paint   21 

—  specification  87,  90 

—  trade  gallon   loi 

Litharge  i>i7 

—  action  on  oil   6 

—  grinding  i,  5,  8 

—  in  paint  for  under  water  use   19 

—  in  red-lead  6,  17,  19,  52 

—  its  proper  use  in  paint  I9>  52 

Louisville  Bridge  44,  56,  57 

Massachusetts  public-works  practise  19,  52,  57 

Mildew   26 

Mill-scale   70 

Mixed  pigments  36,  81 

Navy  specifications  23,  27,  56,  89 

Nickel-plate  R.  R.  bridge   91 

Orange-mineral   2 

Paint,  anti-fouling  56,  60 

—  calculations  76,  80 

—  cost  of   78 

—  finishing  coat  of   31 

—  for  hot  climates   26 

—  light-colored,  for  bridges  32,  35 

 ,  —  tanks  35>  54>  126 

 ,  —  ships  56,  123 

— ,  rough  or  smooth  surface  7>  14 

— ,  thickening  of  6,  8 

—  under  water  19,  26 

— ,  weight  of   76 


Index  137 

PAGE 

Pastes   83 

Pigment,  fine   13 

— ,  specific  gravity  of  82,  83 

— ,  weight  of   82 

Pickling   68 

Pipes,  painting  49>  52 

Railway  cars   60 

Red-lead,  action  on  oil  6,  8,  12,  16 

• — ,  adulteration  of  16,  37 

— ,  change  to  carbonate   17 

— ,  coarse  6,  14 

— ,  color  of  2,  29 

— ,  composition   z 

— ,  Dutch  Boy   10 

— ,  extended   16 

— ,  fine  7,  13,  18 

—  for  glass-making   6 

— ,  high-grade  8,  46 

— ,  how  made  i,  6,  8,  14 

— ,  painters   8 

— ,  paste  10,  64,  87 

— ,  storage-battery   5 

— ,  87  per  cent  14?  17 

— ,  94  per  cent  8,  16 

— ,  97  per  cent   13 

— ,  98  per  cent  8,  13 

Red-lead  paint,  action  of  sulphur  on   36 

 ,  analysis   13 

 ,  application  of   18 

 ,  architectural  use  of   105 

 as  finishing-coat   30 

 as  signal-red   17 

 ,  average   28 

 ,  composition  13,  26,  78 

 ,  cost  of  18,  78 

 does  not  become  brittle   29 

 ,  extra-heavy  28,  48 

 for  oil  refineries,  etc   35 

—  under  water  use  19,  26 


138 


Index 


PAGE 

Red-lead  paint  for  water-tanks  and  pipes   49 

 wood   102 

 ,  former  practice   29 

 ,  formula,  6  lb   28 

 ,  N.  Y.  C   27 

 .  33  lb   27 

 7,  37I  lb  28,  48,  56 

 ,  insulating  quality  of   30 

 ,  permanence  of  color  17?  29 

 ,  stability  of   30 

 ,  successive  coats   26 

 ,  surface-paint   29 

 to  test   62 

Rivet-heads   51 

Rust   71 

Sandblast  60,  67,  131 

Sanitation  64,  68 

Scale   70 

Scraping   70 

Ship-painting  5S>  123 

Shrinking  of  film   51 

Smeaton   73 

Specifications  85,  119 

— ,  architects'   127 

—  for  bridges   119 

 ,  repainting   122 

 gas-holders   127 

 ship-painting   123 

 water-tanks   126 

Spraying   62 

Spreading  capacity   94 

Storage-battery  red-lead   5 

Striping-coat  51^  119,  121,  131 

S  urface-attraction   11 

Tables,  basis  of  10,  76 

—  of  area  97-100 

 pigments   82 

Tanks  19,  49,  54,  126 


Index  139 

PAGE 

Temperature  for  painting   87 

Testing,  red-lead  paint   62 

Thinning  paste  paints   131 

Tinting  colors  21,  30,  132 

Turpentine   22 

—  in  repainting   23 

— ,  mineral  22,  23,  88 

— ,  weight  of   76 

Volume  proportions  3  8,  77 

Wagons  and  automobiles   61 

Weight  of  oil   76 

 pigments  76,  82 

White  paint   32 

Wire-brushing   70 


Wiley  Special  Subject  Catalogues 

For  convenience  a  list  of  the  Wiley  Special  Sub^elk 
Catalogues,  envelope  size,  has  been  printed.  Theat* 
are  arranged  in  groups — each  catalogue  having  a  key 
symbol.  (See  special  Subject  List  Below).  To 
obtain  any  of  these  catalogues,  cend  a  postal  using 
the  key  symbols  of  the  Catalogues  desired* 


1 —  Agriculture.    Animal  Husbandry.    Dairying.  Industrial 
Canning  and  Preserving. 

2 —  ^Architecture.     Building.     Concrete  and  Masonry, 

3 —  Business  Administration  and  Management.  Law. 
Industrial  Processes:  Canning  and  Preserving;    Oil  and  Gas 
Production;  Paint;  Printing;  Sugar  Manufacture;  Textile. 

CHEMISTRY 

4a  General;  Analytical,  Qualitative  and  Quantitative;  Inorganic; 
Organic. 

4b  Electro-  and  Physical;  Food  and  Water;  Industrial;  Medical 
and  Pharmaceutical;  Sugar. 

CIVIL  ENGINEERING 

5a  Unclassified  and  Structural  Engineering. 

5b  Materials  and  Mechanics  of  Construction,  including;  Cement 
and  Concrete;  Excavation  and  Earthwork;  Foundations; 
Masonry. 

5c  Railroads;  Surveying. 

5d  Dams;  Hydraulic  Engineering;  Pumping  and  Hydraulics;  Irri- 
gation Engineering;  River  and  Harbor  Engineering;  Water 
Supply. 


CIVIL  KNGlNKKmNG— Continued 
5e  Highways;    Municipal    Engineering;    Sanitary  Engineering; 
Water  Supply.     Forestry,     Horticulture,   Botany  and 
Landscape  Gardening. 


6— I^esign.  Decoration.  Drawing:  General;  Descriptive 
Geometry;  Kinematics;  Mechanical. 

ELECTRICAL  ENGINEERING— PHYSICS 

7 —  General  and  Unclassified;  Batteries;  Central  Station  Practice; 
Distribution  and  Transmission;  Dynamo-Electro  Machinery; 
Electro-Chemistry  and  Metallurgy;  Measuring  Instruments 
and  Miscellaneous  Apparatus. 


8 —  Astronomy.     Meteorology.     Explosives.     Marine  and 
Naval  Engineering.    Military.    Miscellaneous  Books. 

MATHEMATICS 

9 —  General;  Algebra;  Analytic  and  Plane  Geometry;  Calculus; 
Trigonometry;  Vector  Analysis. 

MECHANICAL  ENGINEERING 

10a  General  and  Unclassified;  Foundry  Practice;  Shop  Practice. 
10b  Gas  Power  and  Internal  Combustion  Engines;  Heating  and 

Ventilation;  Refrigeration. 
10c  Machine  Design  and  Mechanism;  Power  Transmission;  Steam 

Power  and  Power  Plants;  Thermodynamics  and  Heat  Power. 

1 1 —  Mechanics.  ____ 

12 —  Medicine.  Pharmacy.  Medical  and  Pharmaceutical  Chem- 
istry. Sanitary  Science  and  Engineering.  Bacteriology  and 
Biology. 

MINING  ENGINEERING 

13 —  General;  Assaying;  Excavation,  Earthwork,  Tunneling,  Etc.; 
Explosives;  Geology;  Metallurgy;  Mineralogy;  Prospecting; 
Ventilation. 


14-~Food  and  Water.    Sanitation.    Landscape  Gardening. 
Design  and  Decoration.    Housing,  House  Painting. 


/ 


5115 


